Abstract: On the basis of earnestly studying reservoir characteristics and damage mechanism, based on the lab test results, adopted the technology of that preflushing formation before injecting organic solvent, and then removing plug using mud acid to acidize, the problem of acidizing viscous oil well in Jidong oil field was successfully resolved. The technology was used on site for 58 times. The effective times were 42, the effective ratio was 72. 4%. By December 1996, the accumulated incremental oil was 121532 t, good economic benefit was achieved.