Two lubricating greases were prepared by adding nano calcium carbonate and a certain amount of base oil to lithium based grease.One of them only added base oil,while the other added both base oil and nano calcium carbonate simultaneously.The physical and chemical properties of the two lubricating greases,including dispersibility,drop point,cone penetration,oxidation induction period,and apparent viscosity,were tested.Friction tests were also conducted to observe and study the tribological properties of the two lubricating greases,and the effect of the addition of nano calcium carbonate on the performance of the lubricating grease was explored.The results show that the distribution size of nano calcium carbonate in soap base is basically less than 1 μm,and the majority of particle sizes are between 150 nm to 300 nm.After adding base oil and nano calcium carbonate additives to lithium based grease,the droplet point and cone penetration of the grease have little change,while the oxidation performance decreases.The thixotropy of the two lubricating grease is basically the same as that of the base grease.The addition of nano calcium carbonate does not damage the strength of the lubricating grease network structure and does not change the stability of the lubricating grease.At a load of 200 N and a temperature of 50 ℃,the nano calcium carbonate lubricating grease can exhibit good anti-wear performance only after a certain period of running in.However,when the temperature is 100 ℃,the addition of nano CaCO3 may cause an increase in friction pair wear.