The invention provides an insulin aspart precursor. The amino acid sequence is Z1(XY)nZ2Z3Z4-B(1-29)-C1C2C3-A(1-21), wherein Z1, X and Z2 are Asp or Glu respectively, Y is Ala or Gly, n is an integer from 1-10, Z3 is Pro, Glu or Asp, Z4 and C3 are Lys or Arg respectively, C1 and C2 are Glu, Asp, Ala or Gly respectively, B(1-29) is insulin aspart B chain 1-29 bit amino acid, and A(1-21) is insulin aspart A chain 1-21 bit amino acid. The invention also provides a coding gene, a cloning vector or an expression vector containing the coding gene, a transformant, and a method for preparing quick-acting insulin by utilization of the quick-acting insulin aspart precursor protein. The expression level of the product is high, the fermentation expression product purity is high, the extraction method is simple and the yield is high.