In order to improve the diffraction efficiency of light-induced little-period photonic lattices, the periods of written photonic lattice are controled and the diffraction efficiency curve varying with writing time in different angles is recorded by changing the angle between two induced beams when writing one-dimensional photonic lattice in double doped Mg∶Fe∶LN crystal. The results show that the diffraction efficiency of double doped Mg∶Fe∶LN crystal drops sharply when the angle between two induced beam is more than 24°. The intensity oscillation caused by second harmonic increases the diffraction efficiency of photonic lattices. Greater angle between two induced beam makes shorter time of intensity oscillation.