The synthesis and metal ion sensing properties of two new cross-conjugated polymers, poly[(9,9-di-n-hexylfluorene-2,7-diyl)-alt-co-(2-(4-(N,N- (dibutylamino)styryl)benzene)-1,4-diyl)] (P1) and poly[(9,9-di-n-hexylfluorene- 2,7-diyl)-alt-co-(2,5-bis(4- (N,N-(dibutylamino)styryl)benzene)-1,4-diyl)] (P2) are reported. These two polymers show very different sensing characteristics from those observed for linear conjugated polymers. Upon binding with different metal ions, P1 and P2 show clear intensity changes and large shift of their fluorescence emission peaks. This combined response significantly improves their binding selectivity. Moreover, the donor-π-bridge-donor (D-π-D) conjugated side chain motifs on P2 endow it with efficient two-photon absorbing (2PA) property. This allows it to be used in two-photon laser scanning microscopy and sensing.