More and more developers are being attracted by blockchain technologies and sustainable development of various open source blockchain projects. Nevertheless, the various popular programming languages and distinctive blockchain projects could perplex the developers inevitably when they commence to develop systems or applications based on blockchain. So, this paper utilizes a tool named Cloc to count the lines of source code in 12 well-known open source blockchain projects. By further reading codes and documents associated, we try to analyze and compare the programming language constitutions of the projects. Moreover, the paper demonstrates their project sizes and the attention degree to them in the form of charts. Finally, some reference information and suggestions about selections are given to the blockchain developers.