Results of the recombination pumped soft X-ray laser gain experiment of L-like silicon ions are described. The spectra from line-focused laser plasmas on slab silicon targets in 5-12nm region are taken by an 1m unastigmatic grazing incidence grating spectro-graph. The gain coefficients of Si11+5f-3d(8.89nm) and 5d-3p(8.73nm), deduced from the ratio of on-axis to off-axis time-integrated intensity are 1.4cm-1 and 0.9 cm-1, respectively; The corresponding gain coefficients deduced from the growth curve of on-axis intensity with the length of th eline-focused laser plasma are 1.5 cm-1 and 1.4 cm-1, respectively.