  PSR J$1946+3417$ is a millisecond pulsar (MSP) with a spin period
$P\simeq3.17\rm~ms$. Harbored in a binary with an orbital period $P_{\rm
b}\simeq27$ days, the MSP is accompanied by a white dwarf (WD). The masses of
the MSP and the WD were determined to be $1.83\rm~M_\odot$ and
$0.266\rm~M_\odot$, respectively. Specially, its orbital eccentricity is
$e\simeq0.134$, which is challenging the recycling model of MSPs. Assuming that
the neutron star in a binary may collapse to a strange star when its mass
reaches a critical limit, we propose a phase transition (PT) scenario to
account for the origin of the system. The sudden mass loss and the kick induced
by asymmetric collapse during the PT may result in the orbital eccentricity. If
the PT event takes place after the mass transfer ceases, the eccentric orbit
can not be re-circularized in the Hubble time. Aiming at the masses of both
components, we simulate the evolution of the progenitor of PSR J$1946+3417$ via
\texttt{MESA}. The simulations show that a NS / main sequence star binary with
initial masses of $1.4+1.6\rm~M_\odot$ in an initial orbit of 2.59 days will
evolve into a binary consisting of a $2.0\rm~M_\odot$ MSP and a
$0.27\rm~M_\odot$ WD in an orbit of $\sim21.5$ days. Assuming that the
gravitational mass loss fraction during PT is $10\%$, we simulate the effect of
PT via the kick program of \texttt{BSE} with a velocity of $\sigma_{\rm
PT}=60~{\rm km~s}^{-1}$. The results show that the PT scenario can reproduce
the observed orbital period and eccentricity with higher probability then other
values.
