sˈɪns dʒˈɔɪnɪŋ ðə fˈækəlti ʌv ʃˈændɑːŋ jˌuːnɪvˈɜːsᵻɾi ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi sˈɛvən, hiː hˈæzbiːn wˈɜːkɪŋ ˌɔn klˈæsɪkəl pɹˈɑːbləmz ɪn nˈʌmbɚ θˈiəɹi sˈʌtʃ ɐz ˈɛstᵻməts ʌv ˌɛkspənˈɛnʃəl sˈʌmz ˌoʊvɚ pɹˈaɪmz, mˈiːnvˈæljuː θˈiəɹəmz fɔːɹ ɚɹˈɪθmətˌɪk pɹəɡɹˈɛʃənz, ænd ɡˈoʊldbɑːxs kəndʒˈɛktʃɚ.
Since joining the faculty of Shandong University in 1987, he has been working on classical problems in number theory such as estimates of exponential sums over primes, mean-value theorems for arithmetic progressions, and Goldbach's conjecture.