[HB]

in CNMR of aniline, the most deshielded C is that attached to N, I can understand that

I want to know, the order of deshielding is meta,para then ortho (ortho C are the most shielded) I want to understand the cause

[TheUnassuming]

It seems like it would have to do with the electronics of the ring with an electron donating group. 
If you push electrons from the nitrogen into the ring, you can get a negative charge at ortho and para positions.  The meta position never gets a negative charge in the resonance structure and so is more electron poor relative to the ortho and para positions.  The more delta negative ortho/para positions are more shielded by electron density than the more delta positive meta position.  This is also why you get ortho/para substitution with electron donating groups in electrophilic aromatic substitution.