Effect of alloying elements on precipitation of δ phase in Ni-Nb-Cr-Mo alloys has been studied using thermodynamic method. It is found that an increase of Al/Ti ratio or (Al+Ti) content will inhibit the precipitation of δ phase obviously. When the Al/Ti ratio (exceed 1) or (Al+Ti) content increases, Nb content in δ phase increases, while the Mo content decreases. The mole fraction of δ phase increases obviously with increase of Nb content, however, it is nearly not affected by B content. Artificial neural network (ANN) method is tentatively applied to predict the multielement additions on mechanical properties in these alloys. A suitable composition of Al, Ti and B is suggested which obviously promotes stress-rupture life. The theoretical simulation results are finally verified through experiments.