For the traditional Fabry-Perot cavity laser， the field perpendicular to cavity wall will be resonantly enhanced until it breaks with the threshold and escapes out of the cavity， while the field emitted obliquely dissipates outside the cavity leading to the low efficiency. Here a high-efficiency laser cavity is proposed resorting to metamaterials. Based on the multipath positive feedback mechanism， the photons emitted form atoms in any direction can only leak out of the cavity along one direction and no photons run out of the cavity which showed potential for improving the efficiency. Furthermore， this combination of cavity is almost independent of atom position. In addition， we designed a realistic dielectric micro-structure system made of two-dimensional photonic crystals to confirm our proposal. When the gain medium is introduced into the system， the cavity can provide both a lower lasing threshold and a higher maximum emission intensity， compared with the individual zero-index materials cavity， demonstrating improved lasing efficiency.