We demonstrate a scalable architecture for coherent combining of pulsed fiber lasers. A new method for generating synchronous pulsed fiber lasers by direct phase modulation is proposed and investigated. It is shown that phase modulated mutually coupled laser array can be a steady synchronous pulsed fiber laser source. The synchronous pulsed fiber lasers are coherently combined with an invariable phase difference of \pa in adjacent lasers. Neither active phase control nor polarization control is taken in our experiment.