Abstract: Intra-mediate trade plays an important role in the international production system. Service is often inserted into the manufactured goods,service's value always is calculated into the manufactured goods,which leads to the undervaluation of service trade. Firstly,we use forward decomposition method and backward decomposition method to recalculate 40 countries' service trade ratio,we deduce that the global service export is seriously undervalued. Secondly,we recalculate the main economies' export sophistication index,we find that the global export sophistication is generally promoted,but china's export sophistication is less than the average value. Finally,the empirical estimation supports service trade's adhesive function on economic growth,especially service trade's positive effect is better than manufacturing trade.