Abstract: According to one exemplary embodiment, a method for dynamic instance deployment of public cloud uses a load monitor to obtain a current server deployment, wherein the current server deployment at least includes, for each server of a plurality of servers, an identity information of the server, and a number of current connections of the server, a server instance type of the server, and a located area of the server; and uses a scaling engine to determine whether there is at least one server of the plurality of servers satisfies at least one trigger condition, add the at least one server that satisfies the at least one trigger condition into a server candidate set, and receive an information of a performance cost ratio to perform a server scaling procedure for at least one area according to the server candidate set.