The　two-tier　cellular　heterogeneous　networks　that　macro　cells　with　massive　MIMO　overlaid　by　dense　small　cells　can　both　utilize　the　excessive　number　of　antennas　at　the　macro　base　station　and　the　smaller　propagation　distance　in　small　cells.　To　alleviate　the　pilot　contamination　between　the　macro　base　stations　and　improve　the　system　performance,　we　propose　a　transmission　optimization　scheme　using　time-shifted　pilots,　where　the　interferences　both　during　the　pilots　based　channel　estimation　and　data　sending　are　analyzed.　Based　on　this　analysis,　the　users　are　selected　to　be　severed　by　the　small　base　station　allocated　at　the　edge　of　the　macro　cell,　to　have　the　better　ratio　of　the　channel　gains　to　the　inferences.　The　numerical　results　show　that　the　proposed　scheme　effectively　improves　the　data　rates　of　the　systems.