  Magnetic braking (MB) likely plays a vital role in the evolution of low-mass
X-ray binaries (LMXBs). However, it is still uncertain about the physics of MB,
and there are various proposed scenarios for MB in the literature. To examine
and discriminate the efficiency of MB, we investigate the LMXB evolution with
five proposed MB laws. Combining detailed binary evolution calculation with
binary population synthesis, we obtain the expected properties of LMXBs and
their descendants binary millisecond pulsars. We then discuss the strength and
weakness of each MB law by comparing the calculated results with observations.
We conclude that the $\tau$-boosted MB law seems to best match the
observational characteristics.
