You can not directly import an excel/csv file in your smart contracts but you have a few workarounds:
- Convert the data in the csv file into JSON file and use the JSON format in Smart Contracts. (Refer: https://www.blockchain.com/de/api/blockchain_api)
- Process the data in the csv file using client-side script like Javascript and then send this processed data to smart contract.
- Use Oraclize