CubeSats are now becoming increasingly popular for space programs. This is because of their affordability. Moreover, CubeSats can be built using commercial Off-the Shelf (COTS) components. They are cost effective compared with traditional satellites. CubeSats can communicate with each other within a swarm, and with ground station. These capabilities require CubeSats to be equipped with small antennas to facilitate cross-link or downlink communications. Therefore, in this paper, we present a novel design of high gain printed Yagi-Uda antenna and a two element Yagi-Uda antenna array which can be perfectly attached on 3U CubeSat's aluminum bodies to avoid deployment. We have shown a numerical analysis of Yagi antenna array and simulated the antenna using the High Frequency Simulator Structure (HFSS). The simulation model is completed with the existing of CubeSat mental body. Our results show that the antenna array achieves good impedance matching with a return loss of-26.47 dB at the desired frequency of 2.47 GHz, a-10dB impedance bandwidth of 134 MHz (2.396-2.530 GHz) and has a total gain of 6.41dB.