The present study aims to present a new convenient sensor for heavy metals, based on aggregation of citrate-capped- N, N' biphenyl hydrazine 1, 2 dicarbothioamide (PHCA) - modified- (AuNPs). This paper reports a procedure for sensitive and selective spectrophotometric methods for simultaneous determination of mercury (Hg22+) and cadmium (Cd2+). For this aim multivariate data including kinetic spectra of AuNPs were collected during aggregation process. The characterization of AuNPs was performed by transmission electron microscopy (TEM) and Infra-Red (IR) spectroscopy. Partial least square (PLS) regression as an efﬁcient multivariate calibration method was employed to make a connection between the surface plasmon resonance (SPR) spectra of the generated AuNPs. The number of PLS latent variables was optimized by leave-one-out cross-validation utilizing prediction residual error sum of square (PRESS). The linear range was in the range of 3.33 × 10-5 - 3.33 × 10-6 mol L-1 and 2.0 × 10-5 - 1.0 × 10-6 mol L-1, the detection limit was 1.21×10-7 and 0.5 ×10-7 mol L-1 (n=5) for Hg22+and Cd2+, respectively. This method used successfully for simultaneous determination of Hg22+ and Cd2+ in West Azerbaijan regional waters namely Zarineh / Simineh rivers and Urmia Lake.