During the ming dynasty, why did china stop investing in overseas naval expeditions?

The Ming Dynasty stopped to deploy naval ships because the sea was a treacherous place froth with danger. Ship wrecks were very common and as a result, there are many artifacts that sunk in the bottom of the ocean. This was not good business for the Chinese.

Ethnocentrism and concept of "Middle Kingdom" which is very significant for how China see it's place in the world, during Ming dynasty Chinese elites and rulers decided to be more focus on thier own internal affairs, it was shortly after the fall of Mongolian Yuan dynasty when chinese explorations took place, it was seen as the formal policy of the 'foreign dynasty'