This article discusses the legality and reasonableness of the installation fee of telephones. The methods of economical analysis, Iegal analysis and mainly law philosophy are used together to make the issue clear and easy to understand thoroughly. The issue is analyzed specially on the base of China's reality today. The author tries to find the reasonable standard of fees for installing telephones so that it can both be helpful for China's economy, specially the telecommunication industry, and be fair to the customers.