In　this　study,　new　all-d-metal　Heusler　alloys　Fe50-xCr25+xV25(x　=　0-25)　were　investigated　on　the　behaviors　of　atomic　configuration,　lattice　constant　change,　and　ferromagnetism　from　the　aspects　of　theoretical　calculations　and　experiments.　The　theoretical　calculations　found　that　both　end-member　compounds　Fe50Cr25V25(x　=　0)　and　Cr50Fe25V25(x　=　25)　prefer　to　crystallize　in　Hg2CuTi-type　(space　group:　216)　structure　rather　than　Cu2MnAl-type　(space　group:　225)　one.　During　the　whole　substitution　process,　the　structure　of　Fe50-xCr25+xV25　alloys　remains　Hg2CuTi-type　structure,　taking　the　path　from　216　to　216,　but　with　different　degrees　of　BC-site　disorder.　Both　the　experimental　and　theoretical　results　reveal　that　the　lattice　constant　increases　first,　and　then　abnormally　decreases,　showing　a　maximum　at　Cr40,　due　to　the　enhanced　covalent　d-d　hybridizations　between　the　transition　metals.　The　magnetic　moment　and　Curie　temperature　tuned　by　Cr　substitution　vary　remarkably　between　3.3　and　1.15　mu(B)/f.u.　and　between　700　and　170　K,　respectively,　which　indicates　that　the　Cr　substitution　for　Fe　alters　the　spin　polarizations　and　exchange　interactions　in　the　system.　These　results　provide　new　insights　into　the　atomic　configuration,　magnetism　and　bonding　effect　in　all-d-metal　Heusler　alloys　based　on　the　d-d　hybridizations.