  After pumped from $5s_{1/2}$ ground state to $6p_{1/2}$ state, the population
inversion between $6s_{1/2}$ and $5p_{1/2,3/2}$ will be established for
Rubidium four-level active optical clock. In this paper, we calculate AC Stark
shift due to lattice trapping laser which dominates the frequency shift of
clock transition in lattice trapped Rubidium four-level active optical clock.
Several magic wavelengths are found that can form desired optical lattice
trapping potential. By choosing a proper intensity and linewidth of trapping
laser, the fractional frequency uncertainty of clock transition due to AC Stark
shift of trapping laser, is estimated to be below 10^-18
