Since Municipal Solid Waste Incineration (MSWI) bottom ash can be used for a new roadbed material, in order to study the influence of water contents on the strength properties of MSWI bottom ash, the material characteristics were firstly examined. The ultrasonic wave velocity tests, saturated consolidated drained triaxial compression tests, and unconfined compressive strength tests were carried out within the water contents range of 10% to 20%. The results show that the main components of MSWI bottom ash is SiO2, and the best moisture content is about 15.5% with the largest dry density of about 1.52 g·cm-3, which are for well graded gravel soils. Meanwhile, the water content shows significant influence on the strength of MSWI bottom ash, where the ultrasonic wave velocities, uniaxial compressive strength and maximum principal stress difference firstly increase with the water increasing contents, and then gradually decrease, which reaches the maximum values with a water content of approximately 15%. Based on the elastic theory, the relationship between the Poisson's ratio, cohesive force and uniaxial compressive strength of MSWI bottom ash under condition of different water contents was obtained, which provides theoretical basis for further analysis on the strength of MSWI bottom ash.