The invention relates to a multi-service data communication method and communication system for an underwater acoustic network. The multi-service data communication method comprises the steps that 1 a decision node is set to detect and acquire available spectrum resources of underwater low interference, and a common control channel and a number of transmission channels are divided from the resources to generate a threshold value according to the number of the transmission channels; 2 a user node with a communication demand sends the service type information of the transmitted data to the decision node, and the decision node sorts the service type information in order according to a predetermined algorithm and generates a corresponding type value in a one-to-one corresponding manner; and 3 each generated type value is compared with the threshold value. If the type value is less than the threshold value, the user node of the type value is assigned to access a transmission channel for communication. If the type value is not less than the threshold value, waiting for a next time slot is carried out, and returning to the step 1 for re-implementation is carried out.