According to the requirements of offshore piling construction during the construction positioning of offshore piling barge and the reconstruction and expansion of old wharf under complex working conditions，a set of auxiliary positioning system with the functions of accurate navigation of piling barge，real-time three-dimensional display of all elements in the construction positioning process，anti-collision pre alarm of pile body and completion data output is developed. This paper expounds from the aspects of demand analysis，function design，core algorithm，code level implementation and practical application. Through pre-construction control，auxiliary positioning and completion data retention，the system accurately evaluates the construction safety，which can realize all-round accurate control of the positioning process of the entire offshore piling construction and meet the safety and quality control needs of the construction personnel.