With the rapid development of microelectronic devices, efficient thermal management in narrow spaces faces significant challenges. Two-phase heat transfer technology is proposed as a breakthrough in this field; however, big challenges, especially in designing a high-performance wick within limited space, are urgent to be addressed before ultrathin two-phase heat transfer devices (TPHTDs) can be further applied. In this study, a multilayer composite micromesh wick (MCMW), comprised of coarse and fine meshes with different layer combinations, is proposed to enhance the wicking capability, which is promising to further enhance the thermal performance of ultrathin TPHTDs. Capillary rise rate experiments are conducted to evaluate the comprehensive wicking capability. The results show that MCMW structures yield a significant wicking capability enhancement when compared with multilayer single mesh wick (MSMW) structures. The MCMW, consisted of 3 layers of 100-mesh and 3 layers of 300-mesh, exhibits an optimum volumetric flow rate of 14.44 mm(3)/s and an equilibrated wicking height at 55.98 mm. MCMW structure provides a convenient and effective alternative in enhancing the wicking capability of mesh wicks and the thermal performance of ultrathin TPHTDs. (C) 2020 Elsevier Ltd. All rights reserved.