By using a laser profiler, the roughness of ploughed soil surface was obtained. 3D fractal interpolation method was used to interpolate several kinds of reduced measured surface data which were reduced from the original measured ploughed soil surface elevation data in different reduction rates. Also fractal and statistical characteristic parameters were used to compare the original data and the interpolated data. The results show that 3D ploughed soil surface model can be obtained efficiently by the 3D fractal interpolation method with the reduction rate below 80% and the fractal non scale spacing of the dimensions was deduced: the transverse and longitudinal spacing were 23mm and 459mm, respectively. The result provided a theory for choosing the minimum measurement spacing of the ploughed soil and a method for reconstruction of ploughed soil surface.