  In this paper, we use the publicly available observational data of 17 stellar
stars orbiting Sgr A* to test the quantum extension of Schwarzschild spacetime
in loop quantum gravity (LQG). For our purpose, we transform the geodesical
evolution of a massive particle in the quantum-extended Schwarzschild black
hole to the perturbed Kepler problem and calculate the effects of LQG on the
pericentre advance of the stellar stars. With these effects, one is able to
compare them with the publicly available astrometric and spectroscopic data of
stellar stars in the galactic center. We perform Monte Carlo Markov Chain
(MCMC) simulations to probe the possible LQG effects on the orbit of S-stars.
No significant evidence of the quantum-extended Schwarzschild black hole from
LQG is found. Among the posterior analyses of 17 S-stars, the result of S2
gives the strongest bound on the LQG parameter $A_\lambda$, which places an
upper bound at 95\% confidence level on $A_\lambda$ to be $A_\lambda < 0.302$.
