Diode pumped monolithic nonplanar ring laser has the advantages of compactness,reliability and high efficiency.When it was placed in a magnetic field,a unidirectional travelling-wave can be obtained with a high power single-frequency output.270 mW single-frequency,TEM00 output has be obtained from a Nd:YAG monolithic nonplanar ring laser.The working principles of this kind of laser is discussed in detail,and two kinds of new nonplanar cavities are proposed.Because of the similarity of the working principles,these kinds of nonplanar ring cavities are called the pan-triangle nonplanar unidirectional ring cavity.