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We have detected 18642 narrow MgII2796,2803 absorption doublets with 0.2933\lezabs\le 2.6529 in the quasar spectra(DR9Q)of the Baryonic Oscillation Spectroscopic Survey(BOSS).The corresponding catalog is publicly available.Our conducts are limited to thespectral data redwards of the Ly\alpha1216 emission line until the red wing of MgII2800emission line,and to the quasar with median $\langle S/N \rangle\ge 4$ $ pixel^{-1}$ in thesurveyed windows.About 95％of absorbers in our catalog is with $W_r\lambda2796＞0.5$\AA,～and a large fraction(～25％)with Wr2796＞2.0(A).The frequency of detected $MgIIabsorption doublets suggests that our detection would likely be complete when the signal tonoise ratio of $ \lambda2796$ line($ SNR^{\lambda2796}$)is greater than 4.5.Our catalogincludes 13900 doublets with $SNR^{\lambda2796}\ge4.5$.The evolution of the cumulativeincidence rate of MgⅡ absorbers is consistent with previous studies(Seyffert et al.2013; Zhu \&M{\'e}nard 2013),which moderately increases from $z\approx0.4$ to $z\approx1.5$ beforedeclining again toward higher redshift.This evolution fashion is parallel to that of the cosmicstar formation rate density(Madau \& Dickinson 2014).Our catalog contains three kinds ofMgII absorptions that correspond to cosmologically intervening absorptions,environmentalabsorptions and quasar outflow absorptions,respectively.The component of the quasar outflowpeaks at $ v\approx1500～km～s^{-1}$,which is a lower value when compared to the 2000km/sreached through the statistical analysis of CIV absorbers.