The　as-cast　inicrostructure　feature　of　At　sheet　with　high　forming　properties　used　for　pressure　can　manufacturing　pre-treated　by　different　melt-treatment　technique　was　observed　and　analyzed　by　SEM,　EDAX,　TEM　and　selected　area　electron　diffraction　(SAED),　etc.　It　was　found　that　the　oxide　inclusions　in　At　sheet　were　mainly　gamma　-Al2O3,　and　the　Fe-rich　impurity　phases　in　the　sheet　mainly　Al3Fe,　Tl(Al12Fe3Si)　or　(AlFeSiRE).　The　crystal　structure　of　(AlFeSiRE)　phase　was　too　complicated　to　be　determined.　The　effect　of　melt-treatment　technique　on　the　as-cast　microstructure　of　the　sheet　was　remarkable.　There　were　a　number　of　oxide　inclusions　in　the　At　sheet　before　or　after　conventional　melt-treatment,　which　distributed　non-uniformly　and　gathered　together　in　larger　block　shape　with　the　size　of　about　10-40　mu　m.　The　Fe-rich　impurity　phases　in　the　sheet　were　mainly　Al3Fe　and　TI,　and　a　few　of　the　meta-stable　phase　Al6Fe　existed　in　the　sheet.　These　Fe-rich　impurity　phases　appeared　in　a　coarse,　long　needle/flake　or　skeletal　form,　and　were　easily　to　gather　together　with　oxide　inclusions.　When　the　At　sheet　was　treated　by　high-efficient　melt-treatment,　the　amout　of　oxide　inclusions　was　decreased　obviously,　and　these　inclusions　distributed　more　uniformly　in　the　tiny　granular　form　(about　or　less　than　4　mu　m).　The　Fe-rich　impurity　phases　were　mainly　(AlFeSiRE),　and　a　small　amount　of　Al3Fe　phases　also　existed　in　the　material.　The　(AlFeSiRE)　phases　distributed　uniformly　along　grain　boundary　in　tiny　group/sphere　or　short　stick　form.　No　congregation　of　Fe-rich　phases　with　oxide　inclusions　was　found　in　the　material.