Sand flushing, well washing and sand fishing integrated shaft sand removing device and operation method thereof

The invention discloses a sand flushing, well washing and sand fishing integrated shaft sand removing device and an operation method thereof. The sand flushing, well washing and sand fishing integrated shaft sand removing device comprises a sliding sleeve type pitching upper valve assembly, a pump cylinder assembly and a sand ramming pitching lower valve assembly. The sliding sleeve type pitching upper valve assembly comprises a sliding sleeve switch assembly and a pitching upper valve assembly body. The sand ramming pitching lower valve assembly comprises a pitching lower valve assembly body and a sand ramming base cone. A pipe column in the initial state is internally of a full diameter hollow structure so that operation can be conducted in a common hydraulic sand flushing mode; when it is found that negative pressure flow-back does not occur, a lower valve ball and an upper valve ball are put sequentially and made to sit on corresponding valve seats; and hydraulic force with a certain pressure is applied t