[Ashutosh]

in our academic book,it is given that only formaldehyde and benzaldehyde give cannizaro reaction.But concedur (CH3)3C-CHO[2,2-dimethylpropanal],this doesn't contain alfa hydrogen.then this must give cannizaro reaction

[movies]

That compound might be too sterically hindered to undergo the Cannizaro reaction.  It might just not react at all under strongly basic conditions.

I do think that other aldehydes can undergo the Cannizaro reaction though, not just formaldehyde and benzaldehyde.

[Ashutosh]

CANNIZARO REACTION IS CHARACTERISTIC REACTION OF ALDEHYDES THOSE DO NOT HAVE ALPHA HYDROGEN.THEREFORE OTHER ALDEHHDES DO NOT GIVE THIS REACTION.
   PLEASE EXPLAIN STERIC HINDRANCE.
    THANK YOU.

[AWK]

Steric hindrance concerns 2,6 di-substituted benzaldehydes with bulky substituents.
There is another reaction analogous to Cannizzaro reaction, namely Tishchenko reaction in which aldehydes with alpha-hydrogen also react to form esters (not  free acid and alcohol)