In this paper is advanced a new type of collimator-dual sieve-mesh collimator.Its principle is to use scanned electronic beam to attack 400 matrix-arranged wolfram targets of the square holes on the upper side of the main collimator and created 400 small X-ray fields sized by 10mm×10mm.These X-ray fields will leave on its center 400 smaller X-ray fields sized by 5mm×5mm after being further collimated by a sub-collimator. What's more,16 different groups of such X-ray fields can be left on the center of the same field by controlling the all-round movement of the main collimator and sub-collimator in proper order and by scanning it round by round and mesh by mesh with electronic beams.It is these ting fields groups that make up various treatment fields with different energy (Dosage).This type of collimator can replace and simplify all other present collimators on accelerators and conformal-intensity modulation radiotherapy equipments. It has advantage of reducing the costs of radio-therapy equipment and making conformal and intensity modulation radiotherapy easier to perforn.