Breasting dolphin spacing recommended by current codes is relatively simple. When berthing ships have a large range，ships meeting the lower limit may find it difficult or even impossible to berth. To determine the breasting dolphin spacing of large oil wharves with a butterfly layout，this paper compares relevant codes and guidelines in China and other countries，collects data from real ships related to berthing，and analyzes the influencing factors and upper limit of breasting dolphin spacing according to specific projects. The results show that it is necessary to consider the length of ship parallel bodies and the length difference between ship bow and stern parallel bodies caused by the off-center of the manifold center when oil tankers are ballasted in the layout of breasting dolphin and take these indicators as control factors to calculate the upper limit of breasting dolphin spacing.