This paper introduces the migration method of $\boldsymbol{\mu} \mathbf{C}$/OS-II on STM32L with Cortex-M3 core and realizes the example of serial port interrupt and led light task scheduling based on µC/OS-II operating system. A method for low power consumption and wake-up under this platform for the low power mode problem that is not considered on µcos-II is designed. The success of the system transplantation and the stability after transplantation are verified by the serial port task and the LED light. The serial port terminal receiving and receiving function of the pc end is used to verify the correctness of the system interrupt, and the current verification low power mode design is measured by measuring the low power mode. The $\boldsymbol{\mu} \mathbf{C}$/OS-II migration method under the STM32L platform, the design of the serial communication and the design of the low-power mode have practical significance for the future low-power communication devices, which can reduce the workload required for secondary development. Make application development on top of the platform simple.