An under-screen fingerprint sensing device and a fingerprint sensing method are provided. The under-screen fingerprint sensing device includes a fingerprint sensor and a processor. When the fingerprint sensor senses a target object, a first color pixel, a second color pixel, and a third color pixel of the fingerprint sensor respectively output a first color original value, a second color original value, and a third color original value. The processor performs FFC on the first color original value, the second color original value, and the third color original value respectively to generate a first color correction value, a second color correction value, and a third color correction value. The processor determines whether the target object is a real finger according to the first color correction value, the second color correction value, and the third color correction value.