A three-grade protective protector with an upper settling chamber and lower capsules for electrical submersible pump is provided. The protector is assembled from a plurality of standard modules, and comprises a settling chamber and two independent capsules arranged at lower middle part for protection. The utility model has the advantages that the standard modules are combined to form the settling chamber and the two capsules so as to obtain the three-cavity protector with a combined three-grade protection system; the utility model has good protective performance which can satisfy requirement of respiratory capacity of the motor; well fluid and motor oil are separated to avoid corrosion and damage of the submersible motor insulation system caused by the well fluid and prolong service life of the unit assembly; the utility model is convenient for operation and high in safety; the plurality of units can be combined freely; the thrust bearing in the protector has large bearing capacity; the utility model reduce operation cost of the unit assembly, improves price performance ratio and competitive power of the product in market.