Mineral　scaling　and　scaling-induced　wetting　are　critical　issues　in　membrane　distillation　(MD)　during　treatment　of　saline　wastewaters.　Gypsum　scaling　and　scaling-induced　wetting　in　MD　were　successfully　regulated　by　heterogeneous　crystallization　with　in-line　granular　filtration　in　this　study.　Stable　water　recovery　increased　from　32.5　%　to　more　than　52.5　%　in　one-cycle　operation,　depending　on　filter　media　properties.　Because　a　large　mass　of　crystals　were　retained　or/and　adsorbed　in　the　granular　filter,　the　scaling　mass　on　membrane　surface　was　reduced　by　41.2　%,　23.1　%,　54.7　%　and　78.1　%　by　filter　charged　with　activated　carbon,　sand,　fiber　and　activated　alumina,　respectively.　When　activated　carbon,　sand,　fiber　and　activated　alumina　were　used,　the　final　MD　fluxes　were　1.58,　1.04,　1.96　and　3.43　times　that　without　filter,　and　permeate　conductivity　decreased　by　43.0　%,　46.8　%,　83.2　%　and　81.3　%,　respectively.　The　multi-cycle　tests　showed　that　heterogeneous　crystallization　gradually　occurred　in　the　granular　filter,　thereby　promoting　seeding-induced　crystallization　that　reduced　gypsum　scaling　and　scalinginduced　wetting　in　MD.　Excellent　anti-scaling　and　anti-wetting　performance　of　in-line　granular　filtration　was　also　confirmed　for　synthetic　and　real　industrial　wastewater.　The　results　of　this　study　provide　guidance　for　mineral　scaling　control　in　MD　to　allow　resource　utilization　for　saline　wastewater.