As a new kind of flexible pneumatic actuator using clean compressed air as working medium, pneumatic muscle has many particular characteristics comparing with pneumatic cylinder. It can well accord with the development of green transmission technique. Combing pneumatic muscle with mechanical force amplifier is a practical and creative design method. According to this method, two kinds of green pneumatic clamping devices based on two-step orthogonal toggle force amplifier driven by pneumatic muscle are introduced. Their working principles and characteristic features are analyzed and corresponding mechanics calculating formulae are also given respectively.