A channel multiplexing method for reading out detector signals, comprising: step S1: grouping signals of L detectors into M groups, wherein the number of the detectors in each of the groups is at least 2 and at most N, the number of the signals of the detectors in an a-th group is denoted as P(a), L = ∑ a = 1 M P a, the signal of a b-th detector in the a-th group is denoted as Signal(a,b), wherein M≥2, N≥2, 1≤a≤M, 1≤b≤N; step S2: dividing the signals of the L detectors in the step S1 into a first source signal and a second source signal; step S3: providing a first signal transmission line comprising two readout channels A and B, inputting the signals of the detectors into the first signal transmission line at input points along the first signal transmission line between the two readout channels A and B, and providing at least one first signal delay unit between the input points where the signals of the detectors are inputted into the first signal transmission line; step S4: providing a second signal transmission line comprising two readout channels C and D, inputting the signals of the detectors into the second signal transmission line at input points along the second signal transmission line between the two readout channels C and D, and providing at least one second signal delay unit between the input points where the signals of the detectors are inputted into the second signal transmission line; and step S5: symbolizing source detectors which generate the signals and acquiring final pulse information, based on pulses from the four readout channels A, B, C and D, wherein the first signal transmission line and the second transmission line are orthogonal to each other. step S1: grouping signals of L detectors into M groups, wherein the number of the detectors in each of the groups is at least 2 and at most N, the number of the signals of the detectors in an a-th group is denoted as P(a), L = ∑ a = 1 M P a, the signal of a b-th detector in the a-th group is denoted as Signal(a,b), wherein M≥2, N≥2, 1≤a≤M, 1≤b≤N; step S2: dividing the signals of the L detectors in the step S1 into a first source signal and a second source signal; step S3: providing a first signal transmission line comprising two readout channels A and B, inputting the signals of the detectors into the first signal transmission line at input points along the first signal transmission line between the two readout channels A and B, and providing at least one first signal delay unit between the input points where the signals of the detectors are inputted into the first signal transmission line; step S4: providing a second signal transmission line comprising two readout channels C and D, inputting the signals of the detectors into the second signal transmission line at input points along the second signal transmission line between the two readout channels C and D, and providing at least one second signal delay unit between the input points where the signals of the detectors are inputted into the second signal transmission line; and step S5: symbolizing source detectors which generate the signals and acquiring final pulse information, based on pulses from the four readout channels A, B, C and D, wherein the first signal transmission line and the second transmission line are orthogonal to each other.