Abstract: Series 310 new austenitic heat resistant steel was developed for 700 ℃ ultra supercritical boiler. Based on its composition characteristics,its weldability was analyzed,and the welding material and welding process were determined by combined with optional welding material performance contrast. TIG welding experiments were carried out with a small-bore pipe. The mechanical properties of welding joints were tested at room temperature and the stress-rupture property at high temperature of the joints were analyzed. The test results show that the S31035 boiler steel has good weldability,and excellent joint properties and qualified microstructure can be obtained by high matching welding material.