Simplified design of microstrip cross coupled filter is studied. Cross coupling topology of bandpass filter is simplified through suitable constraints on its transmission zeros, while keeping the good stopband performance at the same time. Microstrip structure is considered here to realize cross coupled bandpass filter. Series coupling structure is adopted to minimize the difficulty of tuning the filter. Cross coupling is realized by adding transmission line between the first and the forth resonators. Transmission zeros could be altered by changing the positions of the transmission line, thus additional design flexibility could be obtained. Simulated results validate the proposed methods.