Bitcoin draws the highest degree of attention among cryptocurrencies,while coin mining is one of the most important fashion of profiting in the Bitcoin ecosystem.This paper constructs fresh coin circulation networks by tracking the fresh coin transfer routes through analysis of the transaction referencing in Bitcoin blockchain.A heuristic algorithm is proposed to identify coin miners by comparing coin circulation networks from different mining pools and thereby infer their commonly used mining rewards distribution schemes.Furthermore,this paper characterizes the increasing trend of Bitcoin miner numbers during recent years.