This paper introduces a method for designing a micropower smart level transmitter based on the C8051F410 system-on-chip. The internal AD/DA module is combined with peripheral circuit to complete the collection of voltage and transmission of 4-20mA current. And LCD segment liquid crystal is driven directly by MCU pin to display the current level. And Bubble filtering is used to stabilize the sampling and transmission values. This micro power system is powered by 24V DC power supply and its working current is under 2mA. The system has two ranges (0-20cm, 0-50cm), and gives the actual measured data records of the two ranges. It also analyzes the causes of measurement errors and offers corresponding improvement measures. The design scheme of the system has some reference for designing industrial instrument. KEYWORDS System on a chip, micro power consumption, transmitter.