Tamarix spp. are woody plants that are widely distributed throughout the world, and they have ecological importance in the arid and salinized areas of China. However, methods for modeling the biomass of Tamarix spp. and other multi-stemmed shrubs are inadequate. Diameter measurements (such as diameter at breast height) are frequently used and have proved to correlate well with biomass; however, such methods are difficult to apply for Tamarix because of its irregular growth patterns and multiple stems. Modeling shrub biomass has received more attention in recent years, and several studies have indicated that for shrubs shaped like cylinders or cones, the crown area was significantly correlated with shrub biomass. Considering the constraints of diameter measurements for Tamarix spp., we modeled Tamarix spp. biomass using crown width and height in Changyi Marine Protected Area (Shandong Province, China; 37°06'15"N, 119°22'00"E). The area containing Tamarix spp. (T. chinensis and T. austromongolica) was approximately 20.7 km². In February 2014, nine sample plots (30 m × 30 m) were selected, and three embedded plots (5 m × 5 m) were placed randomly in each plot. Prior to harvesting, the height (H), basal diameter (BD), and crown area (C) of 247 Tamarix individuals in the embedded plots were measured. Fresh weights (FW) were collected after harvesting. At the time of sampling, the trees had no foliage, and thus the FW included only stems and branches. One hundred and eighty-nine individuals were selected randomly to establish the regression equations, while the remaining 58 individuals were used for testing the accuracy of these equations. CH (the product of C×H) and C were chosen as independent variables, and the regression equations were established in the form of linear, power-law, and quadratic polynomials.The equations based on CH were FW=0.856×(CH)－0.879 (R²= 0.884, F = 1428.5), FW=0.403×(CH)^1.226 (R²= 0.900, F = 1396.1), and FW=0.010× (CH)²+0.562× (CH)+0.114(R²= 0.903, F = 875.7), whereas the equations based on C were FW=2.462×C-1.893 (R²= 0.825, F = 881.8), FW=0.900×C^1.440 (R²= 0.861, F = 966.3), and FW=0.144×C²+1.007×C+0.127(R²= 0.864, F = 600.7). Although quadratic polynomial equations had higher R² values, the power-law functions performed best in the test, as they had deviations of -2.22% (CH) and 2.92% (C). Furthermore, because the power-law function is the most widely used allometric equation, we recommend establishing regression equations using power-law functions in this area. As tree crown properties can be reconstructed using high-resolution satellite data, allometric equations that use C as the only independent variable may provide a more cost-efficient way of monitoring, reporting, and verifying the carbon stocks of Tamarix spp. The mean values of H, BD, C, and FW in the study area were (215.2 ± 41.4)cm, (4.2 ± 1.9)cm, (2.49 ± 2.21)m², and (4.15 ± 5.80)kg (mean ± SD), respectively; therefore, artificial management should be enhanced to improve the stand quality.