The invention discloses multiservice frequency assignment method and system for a dual-mode terminal. The method is used for reasonably assigning cable digital television network frequency bandwidth for the DVB/IP (digital video broadcasting and internet protocol) digital television dual-mode terminal and guaranteeing normal service of terminal multi-services. The method includes: when a frequency management unit assigns a certain service-type frequency for the terminal, searching tuner status information and service utilization information corresponding to the dual-mode terminal, and assigning proper frequencies for services of the dual-mode terminal; if an idle turner in the dual-mode server occurs, assigning a frequency meeting the service demanded bandwidth for the dual-mode terminal; and if no idle turner in the dual-mode terminal occurs, switching a service on the original frequency and a newly applied service to a same frequency, and returning frequency switching information. The tuner status information includes tuner number, frequency information locked by tuners, and service information corresponding to the tuners.