  Among a number of gamma ray bursts whose host galaxies are known, GRB971214
stands out for its high redshift $z\ge 3$ and the Ly$\alpha$ emission line
having a P-Cygni type profile, which is interpreted to be a direct consequence
of the expanding supershell. From a profile fitting analysis we estimate the
expansion velocity of the supershell $v_{exp} = 1500\kms$ and the neutral
column density $N_{HI}=10^{20}\cm^{-2}$. The redshift $z=3.418$ of the host
galaxy proposed by Kulkarni et al. (1998) has been revised to be $z=3.425$ from
our profile analysis. The observed Ly$\alpha$ profile is fitted well by a
Gaussian curve, which yields the Ly$\alpha$ luminosity
$L_{Ly\alpha}=(1.8\pm0.8)\times10^{42}\ergs \s^{-1}$. Assuming that the photon
source is a giant H II region, we deduce the electron number density in the H
II region $n_e=(40\pm10) ({R \over {100 \pc}})^{-1.5}\cm^{-3}$, which
corresponds to the illumination by about $10^4$ O5 stars. We estimate the
star-formation rate to be $R_{SF} = (7\pm3){\rm M}_\odot\yr^{-1}$ with the
internal and the Galactic extinction corrected. The theory on the evolution of
supernova remnants is used to propose that the supershell is at the adiabatic
phase, with its radius $R = 18 E_{53}^{1/2} \pc$, its age $t = 4.7\times10^3\
E_{53}^{1/2} \yrs$, and the density of the ambient medium $n_1 = 5.4\
E_{53}^{-1/2}\cm^{-3}$, where $E_{53}= E/10^{53}\ergs$.And we estimate the
kinetic energy of the supershell to be $E_k=7.3\times10^{52} E_{53} \ergs$.
These values are consistent with the hypothesis that the supershell is the
remnant of a gamma ray burst.
