Uniform trace code is the basis for implementing traceability in farm products. A coding scheme that was composed of producing area position code, product code, production date code and attestation type code was designed. Producing area position code was consisted of 13 bits of longitude and latitude, which was converted to ten bits of relative position code and one position identifier by plotting six districts according to the range characters of longitude and latitude in China. Production date code was converted three bits of relative date code and one bit of date identifier. Product code was converted to five bits. The validation code was generated by permutation and combination of position identifier, date identifier and attestation type code. The design of this trace code has the characteristics of short code extent and strong encryption. With it for farm product traceability, the key quality safety information such as production area position, produce date and attestation type can be traced without the support of database.