A mineral material processing plant and a method for controlling thereof. The mineral material processing plant includes at least one motor, at least one actuator, a control system, an arrangement for holding the operating speed of the at least one actuator substantially unchanged. The control system is configured to control the processing plant in such a way that a change of amount and/or quality of material arriving to be processed is recognized and in response to the recognized change of amount and/or quality of the material arriving to be processed, the load of a motor is recognized, and in response to the recognized load of the motor, the running speed of the motor or motors of the mineral material processing plant is increased or decreased so that the operating speed of at least one actuator is held substantially unchanged.