Abstract: This paper discusses the correlation of digitized map coordinates,and to analyze the digitized coordinate data and the errors strictly,adopts adjustment of condition equations with unknowns to solve coordinate conversion parameters.It applies simulating conversion and affine conversion and analyzes the correlation of coordinates conversed by using four known points and nine known points separately.This paper also discusses the distributing rules of the correlation of the grid points.The discussion shows that the x and y coordinates of the same points are not correlative after coordinate translation,but correlation exists in the x and y coordinates of the different points.The number of the known points and the translating manner by which the conversion parameters were drawn determines the correlation of every point.The square error by using nine known points is smaller than that by using four known points after simulating conversion,when the knows points are the same.The precision of ground coordinate after conversion in affine conversion is lower than that in simulating conversion.With the calculating methods adopted in this paper,the value of the correlation changed from-0.235 3 to 0.542 3,which shows that the correlation of the coordinate conversion can not be ignored,and the error analyse should be made on the basis of correlation.