The invention discloses an expansion toy with a water absorbing structure. The expansion toy comprises a base which is arranged horizontally, the inside of the base is a cavity, an end cap is arranged on the upper end face of the base, a water incoming pipe penetrating the end cap is vertically arranged on the end cap, the lower end of the water incoming pipe penetrates the end cap to extend to the bottom of the base, an annular limiting platform which extends outwards is arranged at the upper end of the water incoming pipe, an expansion toy body is arranged at a position, at the upper end of the annular limiting platform, on the water incoming pipe in a sleeved manner, a first branched pipe is obliquely arranged at a position, between the end cap and the annular limiting platform, on the water incoming pipe and communicated with the water incoming pipe, one end, away from the water incoming pipe, of the first branched pipe is connected with a second branched pipe through a flange, a rubber airbag is arranged at the other end of the second branched pipe in a sleeved manner, and a water inlet is arranged in the end cap. The expansion toy is simple in structure, long in service life, capable of providing water itself, simple and reliable, and unexpected injury caused to children when playing by a pond or a river is avoided; the expansion toy is vivid and concrete and good for the children to know natural laws and develop intelligence.