When President Trump threatens China with more tariffs, Lulu thinks of her commission checks and smiles.

It’s a good time to work in the fake-handbag business.

The shadow industry — already a big moneymaker — stands to reap another potential windfall from the trade war.

Knockoffs of famous brands — Coach, Kate Spade and others — are mostly made in China and arrive at U.S. shores through clandestine channels built to dodge authorities. The authentic purses and their components, also made in China, are shipped through official routes and would face Trump’s proposed new duties of 10 percent.

This all stacks up in favor of the counterfeit labels at every step of their illicit journey: from factory floors in China to street vendors in cities worldwide.

Shoppers come to Lulu’s cramped stall in Beijing’s seven-floor Silk Market to get replicas of Coach bags at half-price — cheaper for seasoned bargainers.