Abstract: Some Scholars have proposed that better flexibility indicators for units should include evaluation of startup time, boiler cold start, total time from ignition to turbine inlet impulse starting, and generator grid connection not exceeding 6 hours 1. The cold start time of a 350MW supercritical thermal power unit (from boiler ignition to grid connection) is generally around 9 hours and 10 minutes according to the manufacturer's start curve; Based on the cold start situation of units # 5 and # 6 of a certain company in the past two years, and based on the relevant factors affecting the cold start of the unit, the specific reasons for the differences in cold start of the unit were analyzed. In response to the specific influencing factors, specific measures were taken to shorten the cold start of the unit, thereby shortening the cold start time of the unit from about 9 hours to about 5 hours, and improving the flexibility of the cold start of the unit, Enhanced the competitiveness of units in the thermal power market.