This research aims to examine King Rama lll, King Pranangklao's philosophy of trade and to identify factors influencing the philosophy. Methods of phenomenological philosophy were used to analyze the King's intention to trade that appeared in historical documents and to synthesize His Majesty's philosophy of trade in managing the dynamics of the Asian economy in the 19th century.The results showed that King Rama lll followed a pragmatic philosophy of trade during his reign. This was revealed through a sense of empirical time and space, learning by trial and error, assessment from tangible results and invention of the tax system and free trade system, aiming at achievement. Decision was made by inductive reasoning, including mathematical and statistical data to support innovative trials for exports such as sugar, coffee, junks and vessels, etc. Accepting others' opinions and profit sharing were also included. These are factors influencing his pragmatic trading philosophy: His Majesty the King's intention of being a universal emperor (Cakkavatti) endowed with seven treasures was used to spread the Dhamma to other countries, his belief in human potential, his intention to create works and his intelligence to invent an economic mechanism leading to the outcome of public benefit.