Objective To study the value of the Los Angeles Pre-hospital Stroke Screen (LAPSS) in the diagnosis of pre-hospital stroke. Methods A total of 92 patients in pre-hospital service with neurological symptoms and signs were screened for stroke by LAPSS. The screen Results were compared with the final clinical diagnosis.Results Among the 92 patients, there were 49 patients were identified with stroke by LAPSS. The average time to complete the LAPSS was 280 seconds. The final clinical diagnosis of stroke showed that there were 4 cases of missed diagnosis and 4 cases of error diagnosis by LAPSS. The sensitivity, specificity, and Youden index of LAPSS were 91.8%, 90.7% and 0.83, respectively. The positive and negative likelihood ratio was 9.87 and 0.09, respectively.Conclusions The LAPSS has higher specificity and sensitivity in pre-hospital diagnosis of stroke. It shows important values in emergency treatment of pre-hospital stroke.