Both strain hardening and indenter elastic deformation are unavoidable in most engineering contacts. By the finite element (FE) method, this paper investigates the unloading behavior of elastic-power-law strain hardening half-space frictionlessly indented by elastic sphere for systematic materials. The effects of indenter elasticity on the unloading curve, cavity profile during unloading, and residual indentation of strain hardening contact are analyzed. The unloading curve is observed to follow a power-law relationship, whose exponent is sensitive to strain hardening but independent upon indenter elastic deformation. The indenter elasticity hugely affects the residual indentation of strain hardening materials. Based on the power-law relationship of the unloading curve and the expression of the residual indentation fitted from the FE data, an innovative contact unloading law of strain hardening materials considering the indenter elasticity effect is developed. Its suitability is validated both numerically and experimentally by strain hardening materials contacted by elastic indenter or rigid flat.