A novel derivative of oxytocin containing nonprotein amino acid L-alpha, beta-diaminopropionic acid (L-Dap) was synthesized by 7+2 fragment combination in solution. N beta of all the amino acid necessary was protected by carbobenzoxy (Z) and N beta of L-Dap was protected by tert. -butoxycarbonyl (Boc) . The important intermediate, heptapeptide, was synthesized by the stepwise elongation method using carbobenzoxy amino acid p-nitrophenyl esters in solution. Azide synthesis was used to get the nonapeptide. Z group was removed by treatment with 5% Pd/C and Boc with CF3COOH. Eight new compounds incorporating L-Dap were obtained and confirmed by the amino acid analysis and mass spectral detection.