Type 1&2of  Herpes simplex virus [HSV] is infection causing factor in central nervous system encephalitis in human molecular methods are the best ways to diagnose this pathogen agent. In this study new molecular technique LAMP to determine both types in virus evaluated.  In an experiential study, 184 sample of CSF in Tehran Mofid hospital was provided. Sample of DNA was extracted by DNA Cinaclonekit. A bundle of 6 primers especially for DNA polymerase gene of HSV virus was designed. Reaction product LAMP by increasing saber green was confirmed. The result of LAMP technique by K square test was compared with the result of PCR technique by K square. The sensitivity of modified technique LAMP was up to 5 particle viruses and the sensitivity of PCR technique was up to 50 particle viruses. Both technique LAMP and PCR to diagnose HSV virus types 1, 2 had specificity 100%.From 184 samples CSF according to LAMP technique 60 samples were positive while in PCR technique 45 samples were reported as positive. The sensitivity of LAMP was 10 times higher than PCR technique. Comparing these two methods using K square test showed that this to methods in a meaningful level P