In previous years some 10,000 dogs have been slaughtered and eaten over the 10-day festival.
In the West, reaction is divided between those who vigorously condemn the festival and those who claim that it is a kind of cultural imperialism to judge China by our own values.
Both are half-right and half-wrong.
Take the critics of the festival first. There is certainly plenty for them to truly indignant about.
There is a belief among some that the dog meat tastes better if the animal is slaughtered when distressed, and there are even accusations that the animals are sometimes skinned alive.
READ: Why China needs to stop dog meat festival
Images of dogs of various breeds and sizes crammed in tiny cages and then killed have created an international backlash
READ: Dog meat trade divides China
However, often the critics find it unacceptable that dogs are being caged, killed and eaten at all.
Such complaints are justified when they come from vegans who are equally upset about the conditions of pigs and cows in western industrial farms.
But they are simply hypocritical when they come from carnivores who happily eat intensively reared pigs, or even from vegetarians whose milk and cheese comes from cattle kept in such poor conditions that large swathes of the herds are lame.
However, those who say any criticism at all is a kind of moral imperialism are also guilty of lazy thinking. Almost everyone believes that respect for difference has its limits.
I know of no one who in the name of cultural diversity defends the barbaric practices of ISIS, the chillingly efficient holocaust perpetuated by the Third Reich, or the execution of homosexuals and atheists in some Islamic countries.
What presents itself as open-minded tolerance can very easily become a kind of condescension, as though the Chinese cannot be expected to live up to our highest ideals.
READ: Dog lovers and dog eaters square off
A man chops up dog meat a restaurant in Yulin, Sunday June 21, 2015.
In fact, protest against the Yulin festival began in China, where retired school teacher Yang Xiaoyun paid thousands of dollars to save dogs and cats from the festival, and celebrities such as Chen Kun, Yang Mi and Fan Bingbing have spoken out against it.
Although dog eating is a tradition in parts of China, the Yulin festival was only started in 2009 and is not endorsed by the local government.
What I also find troubling about issues like this is how they insidiously bring out the xenophobe in otherwise liberal people on both sides of the argument.
When I previously wrote about the festival, one person who ranted against me tweeted that all Koreans were evil because they ate dogs.
Such blatantly racist sentiments are rarely expressed so openly but I fear many who condemn the Yulin festival are also confirming their own prejudices about "backward" Asian peoples who are inherently cruel and incapable of being sympathetic towards animals.
The readiness to believe the worst about the Chinese also comes out in the way in which many people sharing their anger on social media accept the stories of cruelty without checking for themselves that they are rife.
Check your objections
Seeing one video of one dog being beaten is not enough to condemn the whole festival, just as knowing that there have been abuses in some Western abattoirs does not condemn the whole meat industry.
Westerners who feel appalled by the Yulin festival need to check that their objections are based on robust values and not just a sentimental preference for cute, friendly animals.
Then, they should check that the stories they hear are true, which it seems they too often are.
Then, they should think hard about the right way to express their disapproval. Some claim that social media pressure from the West has led to a decline in the number of dogs killed to around 1,000, but it is hard to know what is really responsible for the drop.
Usually any perception of outside "Western" pressure is counterproductive for a campaign.
Ultimately this is an issue for the Chinese to resolve themselves.
Backing groups like the Chinese Animal Protection Network shows both respect for the Chinese people and faith in the possibility that some values at least are truly universal.