A double-screw extruder with kneading blocks in a shearing and mixing area capable of automatically changing comprises hollow assembly shafts 2 for assembly of parts, the kneading blocks 1 arranged on the hollow assembly shaft 2, temperature sensors 12 and angle sensors 14, wherein the temperature sensors 12 and the angle sensors 14 are arranged on the kneading blocks 1. A hollow shaft 3 is arranged in each hollow assembly shaft 12. Small-sized power mechanisms 4 and fixed pin controllers 7 are installed on each hollow shaft 3 and connected with an external sensing receiving controller 10 through wires. Each small-sized power mechanism 4 is provided with a planetary gear 5, and each planetary gear 5 and the corresponding kneading block 1 are used for shearing and mixing. Each fixed pin controller 7 is provided with a control shaft 8 connected with a fixed pin 6, and each fixed pin 6 is arranged in a fixed pin groove 11. According to the kneading portion of the double-screw extruder of the above structure, the thickness and the stagger arrangement angle of the kneading blocks in the kneading area can automatically change according to needs, so that the temperature in the machining process is better controlled, and the quality of extruded products is improved.