<p>Traditional threshold signature schemes, which are based on number-theoretic problems, are vulnerable to attacks in quantum computing environments. Moreover, these schemes incur high communication and computational costs among nodes, which pose significant challenges for meeting the stringent requirements of interactive security and real-time performance in power grid load regulation systems. To address these challenges, this paper introduces a post-quantum threshold signature scheme based on CRYSTALS-Dilithium (CDTS) specifically designed for power grid load regulation systems. Constructed within the Fiat-Shamir framework and integrating a CRYSTALS-Dilithium-based threshold signature, this scheme effectively ensures the system’s fault tolerance and security in the face of quantum computing threats. In terms of efficiency, the CDTS scheme significantly reduces computational overheads through the introduction of rejection sampling techniques and the optimization of the number-theoretic transform algorithm. To further enhance the scheme’s adaptability to the dynamic nature of power grid load regulation, an innovative dynamic threshold adjustment mechanism is proposed. This mechanism monitors load changes in real-time within a <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\Delta T\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Δ</mi> <mi>T</mi> </mrow> </math></EquationSource> </InlineEquation> time window, allowing for flexible adjustments to the threshold parameters. Security analysis confirms that the proposed scheme satisfies the security requirements of power grid load regulation systems, making it a robust solution for ensuring secure and efficient load regulation in the quantum era. We conducted rigorous experimental comparisons under the same security level (NIST Level 3) and system scale (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(th=5, n=10\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>t</mi> <mi>h</mi> <mo>=</mo> <mn>5</mn> <mo>,</mo> <mi>n</mi> <mo>=</mo> <mn>10</mn> </mrow> </math></EquationSource> </InlineEquation>), the sizes of the public key (1.32 KB), private key (2.01 KB), and signature (2.45 KB) of the CDTS scheme are almost identical to those of the original Dilithium scheme. This data demonstrates that the threshold construction we proposed is nearly lossless in terms of storage efficiency, significantly outperforming the exponential overhead growth typically brought by traditional scheme. Through rigorous software testing and verification, we evaluated the performance of the CDTS scheme by randomly generating a 59-byte message and iteratively executing the signing process 10,000 times. The results indicate that the CDTS scheme achieves a complete signature and verification process in an average of 506.73 microseconds. This efficiency makes the CDTS scheme highly feasible for practical applications, particularly in environments requiring rapid and secure transaction processing.</p>