This thesis is to study economic change in Monthon Pha-Yap after the construction of the northern railway. It is found that the railway brings convenience for transportation between Monthon Pha-Yap and Bangkok. There is a delivery ready-to-use products from Bangkok, thus the shipment is decreased and the inter-trading is gradually less important. The trading makes Lanna having closer relation with Bangkok. Chinese merchants can extend their roles as controller of the trading network in Monthon Pha-Yap rather than other groups. For the production, the main products of Monthon Pha-Yap are paddy, pigs, fruits and vegetables and handicrafts, so it turns from self reliance to be commercial. Furthermore, Baht currency plays more roles than Rupee currency and this has caused the expansion of urban communities and there are widely social changes. (abstract)