The GB/T 14234-1993 standard specifies the parameters, parameter values and general rules for the surface roughness of plastic parts. The standard is applicable to the surface roughness measurement of plastic parts in the fields of electronics, aviation, aerospace and Instrument, and can also be used as a reference for the surface roughness of Miscellaneous plastic parts. The asperity parameters involved in the standard include the average deviation Ra of contour arithmetic, the height Rz of contour micro-unevenness and the maximum height Rt of contour, and it is recommended to use the average deviation R_a of contour arithmetic. The standard also provides a selection table of different parameter values, and specifies the reachable asperity range according to different processing methods and materials.