The effects of the relative content of Al and Ti, and the addition of 2 at.% Cr or Mo to partly substitute Co on the microstructure and mechanical properties of Co���Ni���Al���Ti superalloy were investigated. The microstructures of five as-cast superalloys showed that ��'-(Co,Ni)3(Al,Ti) precipitates segregated on ��-Co matrix and exhibited dendritic morphology. After aging, nano-sized ��'-(Co,Ni)3(Al,Ti) precipitates uniformly precipitated on ��-Co matrix. Ni, Al, Ti and Mo atoms partitioned preferentially to ����� phase, while Co and Cr atoms partitioned preferentially to �� matrix phase. The increase in Ti content, and the addition of 2 at.% Cr or Mo all increased the volume fraction and the average size of ����� phase. The lattice misfit increased with the concentration of Ti and the addition of 2 at.% Mo, but decreased with the addition of 2 at.% Cr. With increasing aging time, the size of ����� phase and lattice misfit increased, while ����� phase volume fraction increased firstly, and then decreased after reaching the maximum at 100 h. The lattice misfit plays a key role on vicker's hardness in the time of 20 h���100 h aging, while ����� phase volume fraction plays a decisive role in vicker's hardness after 100 h aging.