The invention discloses a comprehensive washing remediation method for heavy 
metal contaminated soil. The comprehensive washing remediation method comprises the following steps: ploughing and smashing soil, applying acid and alkaline washing agent 
solid materials, then drawing water when ploughing, washing and dissolving heavy 
metal out of the soil, and transferring the heavy 
metal into washing water; guiding the washing water into a 
sedimentation tank, adding a coagulant, and removing the heavy metal in the washing water through coagulation and 
sedimentation; draining the washing water into a 
microorganism and 
biochar purifying tank, utilizing 
biochar bags to absorb the heavy metal, and at the same time, enriching the heavy metal through microorganisms on 
biochar surfaces; and collecting used biochar bags, adding a 
dilute acid solution into the biochar bags, stirring, and separating the heavy metal absorbed to the biochar surfaces. The invention further discloses a corresponding comprehensive washing remediation 
system. The technical scheme of the invention greatly increases the 
absorption rate of the heavy metal, avoids heavy metal secondary 
pollution, is simple in technical process, is high in 
automation degree and is low in cost.