In this paper, complementary split ring resonator (SRR) based reflector to enhance the printed slot dipole (PSD) antenna performance is introduced. The numerically calculated return-loss, directivity and radiation pattern results of the PSD antenna, with (w/) and without (w/o) CSRR element etched on reflector plane are presented and investigated. Numerical analysis and modelling of the proposed design are carried out using CST Microwave Studio simulator based on the finite integration technique. According to the simulation results, with the inclusion of the CSRR-based reflector into the PSD antenna, the directivity is increased by values changes from 0.6 dB to 4.25 dB through the operation band, while an improvement in bandwidth (similar to 2.1%) is seen. It is also shown that this improvement in antenna performance is due to the epsilon-negative (ENG) behavior of CSRR structures. Prototype of the proposed antenna is fabricated using Arlon DiClad 880 substrate with electrical permittivity of epsilon(r) = 2.2. A quite good agreement between simulation and measurement is obtained. In this study, it is shown that the radiation performance of the antenna can be increased easily by using the CSRR element as a reflector in the antenna structure with a new enhancement approach. Also, the proposed antenna with a compact size of 0.27 lambda x 0.41 lambda is appropriate for operating in IEEE 802.11b/g/n/ax (2.4 GHz) WLAN applications.