Anticancer drugs which selectively interact with DNA can change DNA's conformation and inhibit the duplication or transcription of DNA. An instrument-based assay for directly screening DNA-targeted anticancer drugs using resonance light scattering (RLS) technique with a common spectrofluorometer was proposed. To monitor the proposed screening method, the interactions between three anticarcinogens (Adriamycin (ADM), Bleomycin A (BLMA), Actinomycin D (ACTD)) and DNA were studied. The sequence of binding constants for the three anticarcinogens obtained from RLS spectra is: K_RLS (ACTD, 9.43 × 10⁵ L mol⁻¹) > K_RLS (ADM, 6.67 × 10⁵ L mol⁻¹) > K_RLS (BLMA, 8.88 × 10³ L mol⁻¹) and of binding numbers is: N_RLS (ACTD, 3.36 mmol g⁻¹) < N_RLS (ADM, 3.81 mmol g⁻¹) < N_RLS (BLMA, 57.44 mmol g⁻¹). From the results we got the sequence of combination intensity between these three drugs and DNA as follows: ACTD-DNA > ADM-DNA > BLMA-DNA, which was completely consistent with drug activity. The conclusion indicated that the present method was direct, rapid, reliable and was another important innovation of the application of RLS technique.