In the paper, a non-API tubing connection’s sealing structure is analyzed through numerical simulation. It is very important for sealing integrity to maintain intimate and usually high contact stress of mating metal surfaces under different loading. First, the contact pressure of main sealing surface and torque shoulder surface generated by interference fit after make-up procedure is analyzed. Then, the variation of contact pressure of sealing system during the load envelope test consisting of the axial loads and internal pressure is analyzed. The analysis results can be used to optimum design and operational suitability test of non-API tubing connections.