  186 binary pulsars are shown in the magnetic field versus spin period (B-P)
dia- gram, and their relations to the millisecond pulsars can be clearly seen.
We declaim a minimum accretion rate for the millisecond pulsar formation both
from the observation and theory. If the accretion rate is lower than the
minimum accretion rate, the pulsar in binary system will not become a
millisecond pulsar after the evolution.
