Former Vice President of Research and Safety at OpenAI and co-founder of Thinking Machines Lab, Lilian Weng, recently officially announced her resignation on the social media platform X. This leading figure in the AI safety field, who graduated from Peking University, stated in her farewell letter that she had been unwell more frequently over the past seven months than any other period in her life, and the sustained pressure and workload had exceeded her body's capacity to handle.

From Peking University to the top of Silicon Valley, after seven years of running, she has now pressed the pause button.

Weng had considered switching to a position with a narrower scope of responsibility, but after weighing the options, she believed that "if I cannot fully commit to the work I should be responsible for, it means I have not done this job properly." In her letter, she left a thought-provoking statement: "A future worth building is one that puts people first" — and admitted that she hopes to join an organization with a stable work rhythm and clear responsibilities in the future, no longer taking on the high-pressure pace of a startup as a co-founder.

Mira Murat, the company's founder and CEO, publicly responded to Weng's tweet, acknowledging her choice to prioritize her health and thanking her for all the contributions she made during her tenure. Weng's resume is a benchmark for Chinese scientists in the AI industry: After joining OpenAI in 2018, she started from the robotics team, built and led a safety systems team of more than 80 people, and was deeply involved in the security development of core models such as GPT-4, GPT-4o, and o1. In August 2024, she was promoted to Vice President of Research and Safety at OpenAI, and left in November of the same year.

In February 2025, she co-founded Thinking Machines Lab with former OpenAI CTO Murat and others. The company just completed a $2 billion seed round of financing in July of this year, with a post-money valuation of $12 billion. At a time when the company's valuation was surging, this co-founder chose to step back due to health issues — this twist itself may reveal more about the true nature of the current AI startup scene, which is marked by high valuations, high pressure, and high consumption, than any industry report could.