A complex full-range spectral domain optical coherence tomography system based on spatial sinusoidal phase modulation is presented. Through sinusoidal phase modulation in the reference arm, the quadrature components of interferogram can be obtained by harmonic detecting. Then the complex-conjugate ambiguity, DC term and autocorrelation noise are eliminated by the Fourier transform of complex interferogram. A complex-conjugate rejection ratio of about 35 dB is achieved. Furthermore, in our experiment, high speed complex-conjugate resolved imaging is performed by combining the sinusoidal phase modulation and transversal scanning.