We present the base sequence effect on the binding properties of G-quadruplex and porphyrin complexes. Change of base composition in loop or at termini of sequences have a significant effect on the stability of final structure. These resulting formations can also effect on the binding properties between G-quadruplex and porphyrin. According to results, once an extra T-base (-TTT-, S2) was placed on loop in sequence 1(-TT-, S1), Their CD spectra was quite different to each other. In contrast, when A-base (5'-A…-TTT-, S3) was added at termini of 5'-side of the sequence 2(-TTT-, S2), there is not induced any structural changes against to S2. On the melting profiles, whether extra base is placed on loop or at termini of 5'-side, less stable than the sequence that without extra base. On the basis of the various spectroscopic results, base composition can effect on the binding properties of porphyrinquadruplex complexes including their stabilities.