Spiral salt washer is used for salt transportation and washing. Salt is spiraldriven for agitated washing and transportation. Wash liquid is sprayed into at the middle of washer for countercurrent washing. Suspending impurities flow out from overflow channel and precipitated impurities is periodically discharged from bottom dirty removing valve. It structure is similar to those of spiral conveyers. It is used for washing up-middle sized salt with better effect being the optimized selection for washing soluble impurities and in-soluble materials.