A signal detection method applied in an electronic device performing fingerprint identification, comprising a display screen (1101, 1301) of the electronic device comprising a plurality of pixel units (101, 1111, 1311) and a plurality of optical sensors (102, 1121, 1321), and positions of the plurality of pixel units (101, 1111, 1311) corresponding to positions of the plurality of optical sensors (102, 1121, 1321) one to one, the method comprising: resetting (301, 901) each optical sensor (102, 1121, 1321) at a first time point; collecting (302, 902) a first signal output by the optical sensor (102, 1121, 1321) at the first time point, a second signal output by the optical sensor (102, 1121, 1321) at a second time point, a third signal output by the optical sensor (102, 1121, 1321) at a third time point, and a fourth signal output by the optical sensor (102, 1121, 1321) at a fourth time point; and obtaining (303, 905) a first difference value between the first signal and the second signal and a second difference value between the third signal and the fourth signal, and determining a sum of the first difference value and the second difference value as a signal variation amount in a current cycle; wherein the first time point is a starting time point of the current cycle, and the fourth time point is an ending time point of the current cycle; the second time point is a time point in the current cycle before a pixel unit (101, 1111, 1311) corresponding to the position of the optical sensor (102, 1121, 1321) performs display; and the third time point is a time point in the current cycle after the pixel unit (101, 1111, 1311) performs display; and wherein after obtaining the first difference value between the first signal and the second signal and the second difference value between the third signal and the fourth signal, and determining the sum of the first difference value and the second difference value as the signal variation amount in the current cycle, the method further comprises: determining that fingerprint identification succeeds when a difference value between the signal variation amount and a preset variation amount of an input fingerprint is smaller than a preset threshold value; and determining that the fingerprint identification fails when the difference value between the signal variation amount and the preset variation amount is not smaller than the preset threshold value. resetting (301, 901) each optical sensor (102, 1121, 1321) at a first time point; collecting (302, 902) a first signal output by the optical sensor (102, 1121, 1321) at the first time point, a second signal output by the optical sensor (102, 1121, 1321) at a second time point, a third signal output by the optical sensor (102, 1121, 1321) at a third time point, and a fourth signal output by the optical sensor (102, 1121, 1321) at a fourth time point; and obtaining (303, 905) a first difference value between the first signal and the second signal and a second difference value between the third signal and the fourth signal, and determining a sum of the first difference value and the second difference value as a signal variation amount in a current cycle; wherein the first time point is a starting time point of the current cycle, and the fourth time point is an ending time point of the current cycle; the second time point is a time point in the current cycle before a pixel unit (101, 1111, 1311) corresponding to the position of the optical sensor (102, 1121, 1321) performs display; and the third time point is a time point in the current cycle after the pixel unit (101, 1111, 1311) performs display; and wherein after obtaining the first difference value between the first signal and the second signal and the second difference value between the third signal and the fourth signal, and determining the sum of the first difference value and the second difference value as the signal variation amount in the current cycle, the method further comprises: determining that fingerprint identification succeeds when a difference value between the signal variation amount and a preset variation amount of an input fingerprint is smaller than a preset threshold value; and determining that the fingerprint identification fails when the difference value between the signal variation amount and the preset variation amount is not smaller than the preset threshold value. determining that fingerprint identification succeeds when a difference value between the signal variation amount and a preset variation amount of an input fingerprint is smaller than a preset threshold value; and determining that the fingerprint identification fails when the difference value between the signal variation amount and the preset variation amount is not smaller than the preset threshold value.