The measurement of crop planting area is essential to yield estimation by remote sensing.The area measuring accuracy directly affects the reliability and applicability of the results.The application of multi-scale remotely sensed data is the inevitable trend.The selection of different scale remotely sensed data sources directly affects the accuracy of measurement of crop planting area.It is necessary and valuable to study the effect of scale on crop planting area measurement

as well as the relationship of qualitative and quantitative research.Therefore

this paper used SPOT5 data and analyzed the scale change effect on the accuracy of measurement by remote sensing.Spatial statistic method and manifold accuracy evaluation indices were respectively used to analyze them with various spatial resolution

spatial extent and crop percentage.And the study results indicate:（1） with the decrease of the spatial resolution

the average regional accuracy will decrease and the errors of crop planting area measurement will increase due to the augmentation of mixed pixels;（2） with the enlargement of the spatial extent of the measuring region

the average regional accuracy increases because the proportions error can be counteracted reciprocally at a certain extent;（3） the percentage of crop can exert a great influence on the choice of data with different spatial resolution used in the measurement of crop planting area.When the percentage of the crop is above 30%

the mean region accuracy at different resolution is basically above 90%.When the percentage reaches 40%—50%

the differences of the mean regional accuracies at different resolution reach the least value and is almost above 93%.With the percentage unceasingly increasing

the mean region accuracies at lower resolution（30m

50m

70m

and 90m） almost keep unchanged.When the percentage of 30m resolution is above 10%

the mean region accuracy can stabilize over 95% even if the measuring extent is small.The results of this paper provide academic and experimental reference to resolve the problem of data selection and accuracy pledge in operational crop planting area measurement by remote sensing.