Abstract: In order to reduce the cost of MCU trim test with high precision requirements and rich functions, a fast and efficient MCU trim test method is proposed. This method controls the output reference and frequency of the circuit through Flash automatic adjustment and compensation of the produced MCU chip, or adjusts the current to realize the effect of automatic adjustment of the MCU chip, and controls the MCU analog output to be output from different pins to the test. Furthermore, the instrument automatically records the test results by the software. The trim test uses an industrial grade 8051 chip. The test results show that through this trimming test method, the MCU can not only meet the output accuracy requirements but also quickly obtain the MCU analog signal output, which effectively reduces the MCU trim test cost.