Problem　representation　is　one　of　the　key　factors　in　problem　solving.　According　to　previous　studies,　PPC　(Posterior　Parietal　Cortex)　is　critical　for　problem　representation.　Whether　does　problem　expression　form　affect　problem　representation?　What　are　the　cognitive　role　of　PPC　in　representation?　In　order　to　answer　these　questions,　a　fMRI　experiment　was　performed　in　this　study　to　examine　the　role　of　PPC　in　problem　solving.　It　was　a　2　×　2　designed　experiment　with　two　2-level　factors:　task　complexity　(one-step　and　two-steps)　and　expression　form　(digits　and　symbols).　In　a　digital　task,　4　digits　are　provided　in　the　initial　grids,　while　4　symbols　of　poker　are　provided　in　a　symbolic　task.　In　a　task　of　one-step,　participants　only　need　one　time　rules　retrieving　to　get　the　target　answer,　while　in　a　task　of　two-steps,　participants　need　two　times　rules　retrieving　to　get　the　answer　of　target　after　getting　the　answer　of　a　bridging　location.　The　results　of　fMRI　show　that　PPC　activated　significantly.　The　further　analysis　shows　that　there　is　a　positive　correlation　between　the　activation　intensity　of　PPC　and　task　complexity,　but　the　correlation　between　the　activation　intensity　of　PPC　and　task　expression　is　not　significant.　According　these　results,　we　infer　that　PPC　plays　an　important　role　in　problem　representation,　maybe　this　representation　is　a　high　level　abstraction.　©　Springer-Verlag　Berlin　Heidelberg　2010.