A combine harvester for rape, rice and wheat comprises a frame, a power mechanism, a header mechanism (1) mounted on the frame, a threshing mechanism (2) and a grain husk separating device (3). The grain husk separating device (3) comprises a vibration cleaning sieve (4), a blowing husk fan (11) and a husk outlet (9). The vibration cleaning sieve (4) includes a vibration cleaning sieve basket (5) driven by the power mechanism, a upper sieve (6) with angle adjustable sieve pieces and a lower net-shaped sieve (7), which are connected with the vibration cleaning sieve basket (5). On one hand, impurity can be further cleaned by adding the sieve with adjustable angle sieve pieces to the vibration cleaning sieve basket. Moreover, the cleaning of the rice, wheat and rape can be taken into account by adjusting the angle of sieve pieces to control the size of sieve mesh, thus realizing a combined harvesting of rice, wheat and rape.
