Recently,a novel π-conjugated microporous frameworks have been attracted a lot of interest for possible application as low-dimensional electronics.1,2 Especially,such structures similar to aza-fused conjugated-microporous-polymer(CMPs)has been successfully synthesized.1 In this work we investigated electronic properties of a series of 2D Benzo-CMPs and their BN co-doped derivatives based on PBE/DFT method using the SIESTA package,as shown in Figure 1 n-Benzo-CMPs(n=3,4,5)can be viewed as n-fused benzenes replacing each double bond in graphene and BN-n-Benzo-CMPs are their corresponding BN co-doped derivatives.The calculated results indicate that all porous graphenes in Figure 1 are semiconductors with a direct band gap from 0.57-1.75eV and can possess nanometer-scale pore size.As pore size increases,the band gap decreases.BN co-doping could make the band gap decreased.The tunable electronic properties via BN co-doping and pore size offered by Benzo-CMPs may be exploited for applications in low-dimensional electronics.