  In this paper we propose a new way to detect sublunar-mass primordial black
holes (PBHs) by direct observations of the Earth-Moon binary system.Our method
is based on treating PBH as a perturbation term, by assuming that the PBH is
far away from the Earth-Moon binary (far greater than 1 AU) and the mass of the
PBH is small (less than the lunar mass). This perturbation treatment allows us
to develop a framework to calculate the orbits of a generic binary system such
as the Earth-Moon binary system. Our numerical results show that the Earth-Moon
distance is sensitive to the initial values of the system. In most cases, the
long-duration interactions between the PBH and the Earth-Moon system can induce
lasting imprints on the Earth-Moon's orbit, and these imprints can accumulate
over time, eventually giving rise to observable deviations which can be used to
infer the properties of the PBH.
