A combustion mode switching control system for diesel engines is provided. The system includes: a switch determination module that initiates a switch request to switch between at least one of a premixed compression ignition (PCI) mode and a diesel combustion mode based on engine speed and at least one of fuel quantity and torque; a transition module that commands the at least one of the PCI mode and the diesel combustion mode based on the switch request; and a control module that controls at least one of target airflow, desired fuel quantity, and desired fuel injection timing based on the command.