Abstract: The calibration method for microscopic parameters in particle flow code (PFC) models of rock materials is investigated based on the contact bond model. Firstly, theoretical deductions of the selected representative unit are made, and the fitting coefficients in the theoretical relationship are obatined through extensive numerical simulations. Finally, the semi-analytic lookup table (SLT) method is established. The researches show that the ratio of contact bond strength has a significant impact on the micro-failure mode of numerical specimens. The representative unit has the same macro-microscopic parameter variation law as the actual PFC models, and the theoretical values of each coefficient are generally consistent with the fitted values. The uniaxial compressive strength and cohesion are linearly correlated with the smaller value between the two contact bond strengths. The calibration of microscopic parameters has a clear sequence. Lastly, the calibration of microscopic parameters for sandstone confirms that the SLT method can achieve a rapid parameter calibration.