A fusion positioning method was proposed based on the correction of UWB distance values to address the problem of low positioning accuracy and poor stability of UWB systems caused by frequent non-visual communication between UWB nodes during the operation of greenhouse plant protection robots. Firstly, a method to identify the communication type between UWB nodes was designed based on the distance residuals; secondly, it analyzed the causes of UWB distance errors under line-of-sight and non-line-of-sight communication and established a distance correction model under the two communication conditions; finally, it designed a method to fuse UWB distance correction values and IMU data based on the extended Kalman filter, and achieved reliable positioning during the operation of greenhouse robots. Finally, the UWB distance correction and IMU data fusion method were designed based on the extended Kalman filter, which finally realized the reliable positioning during the operation of greenhouse robot. The actual validation results showed that the positioning error of the fusion method with UWB range correction was 11.95cm under the non-line-of-sight communication conditions, which was 83.11% lower than that of the fusion method without UWB range correction, and it can provide stable and high-precision positioning information for the greenhouse plant protection robot.