No, you cannot use a dictionary during the HSK 3 test.
The HSK 3 exam is designed to assess your Chinese language proficiency without external aids. You are expected to rely on your own knowledge of vocabulary, grammar, and language skills to complete the listening, reading, and writing sections.
To prepare effectively, it is advisable to focus on building your vocabulary, practicing grammar structures, and improving your listening, reading, and writing abilities through regular study and practice.