With the rapid development of electronic commerce, payment is becoming the focus problem of electronic commerce. Electronic cash has become the ideal method of electronic payment for it is able to realize fair, secure, effect electronic transacts. Along with electronic commerce development, electronic cash payment systems are also gradually developing. However, most electronic cashes are facing the security issues. Moreover, the amount of money each electronic cash card contains is fixed at issuance and is available only within a specified system. The key technology is digital signature technology, including blind signature, group signature, and ring signature. The paper researches the security problems of electronic cash in information safety and e-commerce, and discusses the electronic payment and the security problem, which is regarded as the foundation of electronic commerce. The main factors are given that causes security problems of electronic payment, and suggests corresponding precautionary measures.