Aim\ To solve the problem of marking surface roughness manually in mechanical drafting and improve marking efficiency

surface roughness self marking by computer is adopted. Methods\ A subroutine written with C++ is used to mark surface roughness is given in this paper. Results\ As a related software of size marking system in mechanical drafting

the program has accomplished surface roughness self marking. Conclusion\ The roughness symbols marked with the program can be automatically created in the appointed position. According with the national standard

the marking style is changed with the obliquity of the surface to be marked. The design of surface roughness self marking has certain practical value.