The utility model discloses a pickproof lock for oil storage tank connects protective cover and oil storage tank, including fixing lockpin on the oil storage tank and fixing the tapered end of protective cover one end, the tapered end includes the box body, and sets up inside fixed block, lock core, latch hook, extension spring and the transfer line of box body, box body bottom openings, the latch hook articulates inside the box body, the bottom drawing of this latch hook be with the hook portion that the lockpin agrees with, extension spring one end is fixed on the fixed block, the other end is fixed the bottom of latch hook, the transfer line coupling is in on the lock core, it has the key hole to open on the transfer line, a spacer pin is respectively established to the transfer line both sides, the box body side corresponds open the position in key hole has the through -hole, the transfer line push away to the top of latch hook. The utility model discloses simply, durable, effective theftproof.