Three cottonseed oil ether monoesters were synthesized and structurally identified and they are ethylene glycol methyl ether cottonseed oil monoester, di-ethylene glycol methyl ether cottonseed oil monoester and tri-ethylene glycol methyl ether cottonseed oil monoester. Investigation was made on the effect of ether group number on physicochemical properties of the cottonseed oil ether monoesters. The results showed that density, kinematic viscosity, smoke point, and solidifying point increase linearly with their ether group number in certain relationships. Cetane number is enhanced in a multinomial function whereas heat value decreases linearly with ether group number. When the cottonseed oil ether monoesters were respectively added to the 0# diesel fuel at volumetric content level of 10%(v) and 50%(v), certain regularities were obtained of the properties changing with ether group number. In addition, the influencing regularities of volumetric content of the cottonseed oil ether monoesters on the fuel properties were also studied when the ether monoesters are used as diesel fuel additives.