On the basis of the Contract Law of China, the Parties, as a result of friendly negotiations, have agreed to sign the present Contract for software sales under the following terms and conditions:

On the basis of Contract Law in China, the Parties, ...

if 'the Contract Law of China' is a specific article, then you are correct. If it's a general body of material, then you should refer to it simply as 'Contract Law in China'

1) On the Buyer’s failure of the faithful performance of his obligation of payment by the stipulated date, the Seller shall be entitled to take back (reposess?) the goods by any means. The Buyer shall compensate the economic loss caused to the Seller due to the breach of the Contract, including but not limited to penalty, the freight costs of returned goods and any other expenses incurred.

Alt: On the Buyers failure to faithfully fulfull his payment obligations by the stipulated date, ...

2) Upon agreement by both Parties through consultation: the financial consulting fee and sponsor fee for the reform of the shareholder structure shall refer to the service remunerations and sponsor remunerations that the Buyer shall pay the Seller, including 1,000,000RMB financial consulting fee and the sponsor fee determined by SDB in terms of amount and commission paying method based on the sponsor’s actual performance.

agreement by both parties = consultation, so I think this is repeating the same idea.

Alt: By [or Through] mutual agreement of both parties: the financial ...

The rest looks OK to me. Have a good day ... every day. :)