Artificial　monolayer　black　phosphorus,　so-called　phosphorene,　has　attracted　global　interest　with　its　distinguished　anisotropic,　optoelectronic,　and　electronic　properties.　Here,　we　unraveled　the　shear-induced　direct-to-indirect　gap　transition　and　anisotropy　diminution　in　phosphorene　based　on　first-principles　calculations.　Lattice　dynamic　analysis　demonstrates　that　phosphorene　can　sustain　up　to　10%　applied　shear　strain.　The　bandgap　of　phosphorene　experiences　a　direct-to-　indirect　transition　when　5%　shear　strain　is　applied.　The　electronic　origin　of　the　direct-to-indirect　gap　transition　from　1.54　eV　at　ambient　conditions　to　1.22　eV　at　10%　shear　strain　for　phosphorene　is　explored.　In　addition,　the　anisotropy　diminution　in　phosphorene　is　discussed　by　calculating　the　maximum　sound　velocities,　effective　mass,　and　decomposed　charge　density,　which　signals　the　undesired　shear-induced　direct-to-indirect　gap　transition　in　applications　of　phosphorene　for　electronics　and　optoelectronics.　On　the　other　hand,　the　shear-induced　electronic　anisotropy　properties　suggest　that　phosphorene　can　be　applied　as　the　switcher　in　nanoelectronic　applications.　©　2015　IOP　Publishing　Ltd.