This paper presents an wideband stripline balun. And, the proposed balun is composed of one power divider and two phase converters on stripline substrate. The target characteristics of the proposed balun is the combination loss of below -0.05 dB, an amplitude imbalance of ${pm}0.5;dB$ and a phase imbalance of $180{pm}10$ degrees, with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1500 MHz. The fabricated balun occupies the area of $12(W){ imes}220(L){ imes}2.3(T);mm3$. Experimental measurement shows that the fabricated balun has an amplitude imbalance of ${pm}0.7;dB$, a phase imbalance of $180{pm}8$ degrees and an insertion loss of about -2 dB with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1,500 MHz.