In this paper a completely new type of solid-state round traveling-wave laser is presented. A Nd∶YAG crystal is used as gain medium. Its resonator consists of only two concave mirrors (one of them is directly coated on the laser crystal surface), between which laser beam travels along a closed 3-dimensional loop. Steady oscillation of many kinds of round traveling-wave lasers has been observed. The laser experiment results indicated that the novel laser has simple structure and stable output. Based on the new structure of the new type of solid-state lasers, high-power high-efficient lasers with high beam quality can be developed by end-pumping at multi-points on the laser crystal. High-efficient single-frequency laser and mode-locked laser with short cavity length can also be developed by means of suitable design.