The invention discloses a control system and method for an industrial heat load group to participate in primary frequency modulation of a grid. The control system includes a primary frequency modulation compensation controller which is configured to generate a load compensation instruction for a heat load group to participate in primary frequency modulation of a grid according to the frequency fluctuation deviation value of the grid and the set value of power of the heat load group, and a toggle switch which is configured to carry out primary frequency modulation function switching according to the operation demand of a heat load group system and the grid. A heat load group controller is configured to determine whether each heat load subset meets the conditions for participating in primaryfrequency modulation, and if each heat load subset meets the conditions for participating in primary frequency modulation, calculate the amount of primary frequency modulation load distributed to each heat load subset in the heat load group, automatically calculate the duration of the heat load group participating in primary frequency modulation of the grid, and automatically switch off the heatload group if the heat load group is timed out. Each heat load subset is configured to complete corresponding load regulation according to the amount of primary frequency modulation load distributed by the heat load group controller.