The invention discloses a primary frequency modulation assessment index calculation method based on time point comprehensive processing. According to requirements in state-specified standards of GB/T 30370-2013 and Q/GDW 669-2011, based on the real-time power value and the frequency value of a unit acquired by a power grid main station end, the rotation speed change rate L3 of the unit at a 3s time, the rotation speed change rate L15 of the unit at a 15s time and the rotation speed change rate L30 of the unit at a 30s time are calculated respectively, greatest option processing is carried out on the three calculated rotation speed change rates L3, L15 and L30, the greatest value L is comprehensively used as a rotation speed change rate in the primary frequency modulation performance indexes of the unit for assessment, and whether the primary frequency modulation is qualified is judged. Multipoint rotation speed change rate calculation can be carried out, the primary frequency modulation assessment index effectiveness and the accuracy are enhanced, the unit is ensured to meet primary frequency modulation action working quickness and stability requirements by the power grid, and the power grid is ensured to operate safely and stably.