A　digital　photographic　study　of　pool　boiling　with　binary　mixture　R11(CCl3)-R113(CCl3CF3)　was　performed　on　a　horizontal　transparent　heater　at　pressure　of　0.1　MPa.　A　high　speed　digital　camera　was　applied　to　record　the　bubble　behaviors　in　boiling　process.　Strong　effects　of　composition　on　bubble　departure　diameter,　departure　time,　nucleation　density　were　observed,　which　was　attributed　to　the　nature　of　the　activation　of　the　boiling　surface　and　mass　diffusion　effects.　The　bubble　departure　diameter,　departure　period　and　nucleation　density　as　functions　of　composition　for　binary　mixtures　R11-R113　were　presented　respectively.　From　the　video　images,　it　can　be　concluded　that　evaporation　of　microlayer　is　very　important　to　the　growth　of　bubble.　It　is　also　observed　that　there　is　not　any　liquid　recruited　into　the　microlayer　below　the　bubble.