In　the　era　of　information　explosion,　the　demand　of　data　storage　is　increased　dramatically.　Holographic　data　storage　technology　is　one　of　the　most　promising　next-generation　data　storage　technologies　due　to　its　high　storage　density,　fast　data　transfer　rate,　long　data　life　time　and　less　energy　consumption.　Collinear　holographic　data　storage　technology　is　the　typical　solution　of　the　holographic　data　storage　technology　which　owns　a　more　compact,　compatible　and　practical　sys-tem.　This　paper　gives　a　brief　review　of　holographic　data　storage,　introduces　collinear　holographic　data　storage　technolo-gy　and　discusses　phase　modulation　technology　being　used　in　the　holographic　data　storage　system　to　achieve　higher　storage　density　and　higher　data　transfer　rate.