SCN3 is one of the most destruction diseases which is hard to cure when infected .Though effective ,i ts price and pollution makes chemical medicine unusable .The most ef fective and economical w ay as to use theresistance inherent in the plant .The fi rst step of cultivating resistant cultivar is the choosing and identify ing resistantgermplasm .Wild , semi -w ild and cult ivated resistant or suscept ible to SCN3 material is used in thisstudy .Total phenolicis is measured to SCN3 to determine the biochemical mechanism of SCN3 resistance .Theinvasion process discussed .The aim is to disclose to internal reg ularity of cultivar resistance , so to lay academicfoundat ion for choosing , identifying and cultivity SCN3 resistant material.The results show , total phenolicis isone of identifying biochemical indexes .The best identifying period is the later period .