CdxZn1-xSe alloy nanocrystals (NCs) were successfully synthesized by an organic route using oleic acid as a capping agent. The molar ratio of Cd/Zn strongly impact on the PL properties of the alloy NCs. The PL peak wavelength of the alloy NCs was 565 nm at the Cd/Zn molar ratio of 0.05 while their wavelength became 621 nm in the case of the molar ratio of 1. The average lifetime of the alloy NCs increased with increasing the Cd/Zn molar ratios (26 ns for a ratio of 0.05 and 45 ns for a ratio of 1). The X-ray diffraction analysis indicated that the alloy NCs revealed a cubic structure. The Cd/Zn molar ratio drastically affected the crystal structure of the alloy NCs which located between those of ZnSe and CdSe NCs.