Tongji-1 (TJ-1) lunar soil simulant has been developed as a substitutive material of lunar mare for the purpose of engineering and scientific research. The moisture content and gradation are significant factors influencing the mechanical properties of TJ-1 lunar soil simulant. Their variation is hardly avoided if TJ-1 lunar simulant is manufactured in large quantities. This paper investigates the effects of moisture content and gradation on the mechanical properties (e.g. strength parameters

deformability) in TJ-1 lunar simulant. A series of mechanical tests were designed and performed for TJ-1 lunar soil simulant at different moisture contents and different gradations. The experimental results demonstrate: the upper limit of the moisture content is 3%; the relationship between strength parameters and moisture content and the acceptable range of gradation are obtained.