The invention provides a distribution method and a system for heat-engine plant plant-level loads, wherein the method comprises the steps of obtaining load limit and load energy consumption properties of each generating set in multiple generating sets, according to the obtained load limit and the load energy consumption properties of each generating set and a planned total load value, calculating a load distribution plan, and according to the obtained load distribution plan, distributing loads for each generating set so as to meet the facts that the obtained loads distributed for each generating set is within the load limit of each generating set, the sum of the obtained loads of the multiple generating sets is equal to the plan total load value, and obtained total energy consumption of the multiple generating sets is the lowest. According to the technical scheme, optimization and load distribution of the plant-level generating sets can be automatically and reasonably conducted according to the load energy consumption properties, adjustment rates, load adjustment limits and operation conditions of the generating sets, and therefore the total energy consumption of the whole plant is enabled to be the lowest under the premise that the plan total load value is met.