In view of the problem that the restrictive condition“when bc＞B，then bc=B” in the current JTS 167—2018 Design Code for Wharf Structures for the formula b′c=0.5bc+y for calculating width of bending moment under offset load will lead to the larger calculation result of internal force when the plate width B is less than 0.5l0，we make a comparative analysis of the relevant provisions in the current code JTS 167—2018 and the old code JTJ 291—1998，and compare the bending moment and internal force results of slab under concentrated load calculated by the finite element software and the code formula. The results show that the restrictive conditions “when b′c＞B，then b′c=B；when b′c＜B，then b′c=0.5bc+y”for the formula b′c=0.5bc+y for calculating width of bending moment under offset load is more in line with the actual situation.