The infrared spectra and resistivity of La1.85Sr0.15Cu1-yTiyO4 (0≤y≤0.06) and La2-xSrxCu0.94Ti0.06O4 (0.15≤x≤0.31) samples are studied. It is found that the resistivities of La1.85Sr0.15Cu1-yTiyO4 samples are larger than that of La2-xSrxCu0.94Ti0.06O4 samples. Especially, in the vicinity of the superconducting transition temperature (Tc∼37.8 K) of La1.85Sr0.15CuO4, the resistivity for the end composition compound La1.85Sr0.15Cu0.94Ti0.06O4 is about two orders of magnitude higher than that for compound La2-xSrxCu0.94Ti0.06O4 with x=0.16. Two infrared transmission peaks located at ν1=503 cm-1 and ν2=680 cm-1 are assigned to the stretching mode of apical oxygen atoms out of Cu–O plane and- the stretching mode of oxygen atoms in Cu–O plane, respectively. The results indicate that the appearance of the ν2 peak for La1.85Sr0.15Cu1-yTiyO4 series samples and the disappearance of ν2 peak for La2-xSrxCu0.94Ti0.06O4 series samples are always related to the change of the hole carrier concentration in the two systems. The observed phenomena are discussed from the viewpoint of the charge carrier compensation effect.