a head part building block,

a body part building block,

limbs part building blocks, and

a combined part building block,

wherein the body part building block and the combined part building block are spliced into an assembly hole in a movable gear of the head part building block through splicing pillars; in turning the body part building block, the combined part building block or the head part building block, the movable gear in the head part building block plucks a sounding plectrum to make a bouncing mechanical sound;

wherein the limbs part building blocks are spliced into limbs installation cavities of the body part building block through splicing buckles;

wherein barbs on the splicing buckles cooperate with barb steps in the limbs installation cavities;

wherein each of the limbs part building blocks consists of a limbs part building block base, a limbs part building block cover and first magnets, the first magnets are placed in first foot movable cavities formed by the limbs part building block base and the limbs part building block cover; magnetic poles of the first magnets are fixed and can rotate freely in the first foot movable cavities; and the limbs part building block base and the limbs part building block cover form the splicing buckle which is provided with the barb;

wherein the combined part building block consists of a combined part building block base, a combined part building block cover, a splicing pillar and second magnets; the splicing pillar is placed in a movable cavity formed by the combined part building block base and the combined part building block cover, and can rotate around an axis; the second magnets are placed in second foot movable cavities formed by the combined part building block base and the combined part building block cover; and magnetic poles of the second magnets are fixed and can rotate freely in the second foot movable cavities to change an external magnetic pole; and

wherein the first magnets are not configured to connect the limbs part building blocks to the head part building block, the body part building block, or the combined part building block, and the second magnets are not configured to connect the combined part building block to the head part building block, the body part building block, or the limbs part building blocks.