Abstract: In order to improve the performance of sunlight conveyor,a new tracking system,which combines the open-loop and closed loop mode is proposed based on the STM32 controller as the master chip.After analyzing the weather condition,it can select and use the suitable working mode.The system uses the pulse width modulation to drive stepper motor,which reflects the advantages of fast response performance,good dynamic immunity and smooth low speed operation and so on,guaranteeing the tracking performance and accuracy of the system.Experimental result shows that the error of improved tracking system is less than 0.1,the sunlight conveyer works stably and reliably,and the system can work normally at the complex weather condition.