A method of calibrating time in a Positron Emission Tomography (PET) device, the method comprising: obtaining original time information and energy information of a first pulse signal collected by a detecting module during a scanning process of the PET device, wherein a detector of the PET device comprises a plurality of detecting modules, the original time information of the first pulse signal comprises a moment at which an amplitude of the first pulse signal begins to be greater than a threshold, and the energy information of the first pulse signal is determined by performing a numerical integration for amplitude information of the first pulse signal; determining a pulse time calibration amount corresponding to the energy information of the first pulse signal according to stored information indicative of a correspondence between the pulse time calibration amount and the energy information of each detecting module, wherein the correspondence of each detecting module is a linear function, the linear function i being: deltaT = a × E + b ; wherein deltaT represents the pulse time calibration amount of the first pulse signal, E represents the energy information of the first pulse signal, a and b represents function parameters of the linear function; generating calibrated time information of the first pulse signal by calibrating the original time information with the pulse time calibration amount; and reconstructing a PET image based on the generated calibrated time information. obtaining original time information and energy information of a first pulse signal collected by a detecting module during a scanning process of the PET device, wherein a detector of the PET device comprises a plurality of detecting modules, the original time information of the first pulse signal comprises a moment at which an amplitude of the first pulse signal begins to be greater than a threshold, and the energy information of the first pulse signal is determined by performing a numerical integration for amplitude information of the first pulse signal; determining a pulse time calibration amount corresponding to the energy information of the first pulse signal according to stored information indicative of a correspondence between the pulse time calibration amount and the energy information of each detecting module, wherein the correspondence of each detecting module is a linear function, the linear function i being: deltaT = a × E + b ; wherein deltaT represents the pulse time calibration amount of the first pulse signal, E represents the energy information of the first pulse signal, a and b represents function parameters of the linear function; generating calibrated time information of the first pulse signal by calibrating the original time information with the pulse time calibration amount; and reconstructing a PET image based on the generated calibrated time information. wherein deltaT represents the pulse time calibration amount of the first pulse signal, E represents the energy information of the first pulse signal, a and b represents function parameters of the linear function; generating calibrated time information of the first pulse signal by calibrating the original time information with the pulse time calibration amount; and reconstructing a PET image based on the generated calibrated time information. <EOS>