Abstract: To evaluate swathing efficiency during agricultural machinery operation, swath overalp and skip areas were analyzed by GIS spatial analysis methods based on GPS track logs. Some assessment indexes including overlap rate for field and skip rate for field indicating agricultural machinery operation quality were proposed in this paper. Overlap rate and skip rate of some fields in different agricultural applications were calculated based on GPS track logs of agricultural machinery. In wheat harvest, overlap rate was more than skip rate, and the highest overlap rate was up to 13.30%. In fertilizer application, skip rate was more than overlap rate and the highest skip rate was up to 13.80%. In pesticide application, overlap rate was more than skip rate and the highest overlap rate was up to 12.93%. The above results reflected the actual operation situation. These results showed that there was obviously overlap or skip between swaths during agricultural machinery operation without guidance, which could lead to high operation costs, low swathing efficiency and even affect farmland environment safety. The research provides an effective evaluation tool for agricultural machinery operation supervision.