Present situation of 550 kV SF6 gas insulated switchgear（GIS）all over the world is introduced

and the technical parameters and structural characteristics of compact 550 kV GIS are especially explained. Rated cur-rent of 6 300 A and rated breaking current of 63 k A are achieved. For the mechanical endurance test of gas cir-cuit breaker（GCB）

M2 level can be achieved in all of the disconnect switch（DS） and earthing switches（ES）. The GCB is designed with structure of single-break without parallel capacitors in the arc-extinguishing

and driv-en by integrated hydraulic mechanism. Integrated and modular design has been used in DS and ES and the char-acteristics of low cost

simple structure have been realized. Through the simulation of overall of GIS and the key components

the GCB+DS/ES+CT can be installed

debugged and transported as a whole

which decreases the time of test in factory and cuts down the cost of transportation

and improves the efficiency and quality. The stability of the quality of product can be ensured. This device has been developed with independent intellectual property rights

which can help to realize miniaturization and lower cost

and the layout can be more reasonable. A full set of type testing has been carried out. And the successful development of the device can contribute to a great social significance.