The present invention discloses a computational distributed fiber-optic sensing method and system. The method includes: determining a signal source for modulating intensity of incident light, where the signal source is a binary sequence; using an optical pulse sequence obtained after modulation is performed using the signal source, as an incident light signal, and emitting the incident light signal to an optical fiber; acquiring, according to specified sampling frequency, a scattered light signal obtained through optical fiber scattering; determining, according to the incident light signal and the scattered light signal, a time-domain reconstructed image of a to-be-detected light signal by using a time domain-based differential ghost imaging protocol; and determining a sensing signal of the optical fiber according to the time-domain reconstructed image of the to-be-detected light signal. The computational distributed fiber-optic sensing method and system provided in the present invention feature low sampling frequency, low device complexity, and low costs.